UNIVERSITY  OF  CALIFORNIA 

ANDREW 

SMITH 

HALLIDIE: 


...  I  -,:/:,;.Y,  ,.--. 

" "  •     ' 


LOCOMOTIVE  SPARKS. 


BY 

W.   F.    M. 


DEAN    OF    THE    SCHOOLS    OF    ENGINEERING 

AND 

DIRECTOR    OF    THE    ENGINEERING    LABORATORY, 
PURDUE    UNIVERSITY. 


FIRST    EDITION. 
FIRST    THOUSAND. 


NEW  YORK: 

JOHN  WILEY  &  SONS. 

LONDON:  CHAPMAN  &  HALL,   LIMITED. 

1902. 


^ 


fcu 


Copyright,  1902, 

BV 
W.  F.  M.  GOSS. 


ROBERT    DRUMMOND,    PRINTER,     NEW   YORK. 


PREFACE. 


A  STUDY  of  fuel-losses  from  locomotives,  in  the  form  of 
sparks,  was  first  made  by  the  author  in  1896.  From  this  study 
the  work  has  gradually  been  extended  to  embrace  other  phases 
of  the  spark  problem  until  a  considerable  amount  of  data  has 
been  collected.  Meanwhile,  a  description  of  the  early  work 
having  been  published,  there  were  received  at  the  laboratory 
so  many  inquiries  for  information  concerning  sparks  that  it 
has  seemed  best  to  summarize  and  publish  the  facts  now  in 
hand.  In  selecting  data  for  presentation,  an  effort  has  been 
made  to  serve  students  of  locomotive  performance  as  well  as 
those  who  may  be  concerned  with  more  practical  problems. 
Facts  are  presented  which  it  is  hoped  will  be  found  useful  to 
those  who  have  to  deal  with  fuel  saving,  those  who  may  be 
interested  in  the  design  of  spark-arresters  or  front-end  appli- 
ances, and  those  who  are  concerned  with  the  dangers  of  acci- 
dental fires  from  sparks. 

Acknowledgment  is  due  Messrs.  Lewis  S.  Kinnaird,  Alfred 
R.  Kipp,  George  F.  Mug,  Charles  Ducas,  and  Jay  B.  Dill, 
who,  while  students  at  Purdue,  were  interested  in  advancing 
some  phase  of  the  whole  research.  Published  results  which 
have  been  most  valuable  are  those  of  Messrs.  Robert  Quayle, 
Edwin  M.  Herr,  Charles  H.  Quereau,  Herr  von  Borries,  and 


116756 


iv  PREFACE. 

Mr.  J.  Snowden  Bell.  Individual  credit  is,  so  far  as  prac- 
ticable, given  elsewhere.  The  author  is  especially  indebted 
to  Mr.  Ducas  for  courteous  and  generous  assistance  in  the  ar- 
rangement of  data  for  publication,  and  in  the  preparation  of 
illustrations. 

W.  F.  M.  G. 

ENGINEERING  LABORATORY,  PURDUE  UNIVERSITY, 
LAFAYETTE,   IND.,  October,  1901. 


TABLE  OF  CONTENTS. 


CHAPTER    I. 

THE    LOCOMOTIVE. 

PAGE 

I.   Fundamental  Conceptions  ......................................        r 


CHAPTER    II. 

CONDITIONS    AFFECTING    FURNACE    ACTION    IN    A    LOCOMOTIVE. 

2.  The  Locomotive-furnace  ........................................  7 

3.  Rates  of  Combustion  in  the  Furnaces  of  Locomotives  ............  g 

4.  Rates  of  Combustion  and  Grate-areas  ..........................  10 

5-   Draft  .........  .  ............................................  ....  14 

CHAPTER    III. 

CINDERS    AND    SPARKS. 

6.  How  Cinders  are  Made  .........................................  T6 

7.  Front-end    Cinders  .............................................  I7 

8.  Sparks  .......................................................  18 

g.  Conditions  Affecting  the  Production  of  Cinders  and  Sparks  ......  18 

10.  Experiments  to  Determine  the  Extent  of  Spark-losses  ............  ig 

11.  Size  of  Front-end  Cinders  and  Sparks  ...........................  21 

12.  The  Loss  of  Fuel  by  Cinders  and  Sparks  ........................  27 

13.  Heating  Value  and  Coal  Equivalent  of  Sparks  ...................  33 

14.  Conclusions  as  to  Cinder-  and  Spark-losses  ......................  35 

CHAPTER    IV. 

SPARK    PREVENTION  —  FRONT-END    ARRANGEMENTS. 

15.  Spark  Prevention  ..............................................  37 

16.  Increased  Grate-area  .................................  .........  37 

v 


VI  TABLE   OF  CONTENTS. 

PAGE 

17.  The  Brick  Arch 38- 

18.  A  Typical  Front-end 38 

19.  Diaphragm  or  Baffle-plate 41 

20 .  Netting 43 

21.  Petticoat-pipe 45 

22.  Exhaust-pipe 46 

23.  Exhaust-tip 49 

24.  Smoke-stack 50 

25.  Extended  Front-end 50 

26.  Practice  in  Front-end  Arrangements 53 

27.  Authorities  on  the  Front-end 72 


CHAPTER    V. 

THE   ACTION    OF    THE    EXHAUST-JET   AND   THE    DISTRIBUTION    OF   SPARKS 
WITHIN    THE    STACK. 

28.  Experiments  to  Determine  the  Character  of  the  Exhaust-jet 74 

29.  The  Action  of  the  Exhaust-jet 79 

30.  Distribution  of  Sparks  within  the  Stack 85 


CHAPTER    VI. 

SPREAD    OF    SPARKS    AS    DISCLOSED    BY    OBSERVATIONS    ALONG 
THE    RIGHT-OF-WAY. 

31.  Experiments  and  Results. . .' 89 

32.  A  Summarized  Statement  of  Results 128 


CHAPTER    VII. 

THEORETICAL    CONSIDERATIONS    AFFECTING   THE    SPREAD    OF    SPARKS 
BY    MOVING    LOCOMOTIVES. 

33.  Purpose 129 

34.  Preliminary  Conceptions 129 

35.  The  Horizontal  Displacement  of  a  Body  in  Air  under  the  Influ- 

ence of  Gravity  and  the  Wind 130 

36.  The    Horizontal  Displacement    of   a    Body  Projected    Vertically 

Upwards  under  the  Influence  of  Gravity  and  the  Wind 133 

37.  The  Horizontal  Displacement  of  Sparks 136 

38.  The  Effect  of  the  Direction  of  the  Wind  on  the  Distance  from  the 

Track  to  which  Sparks  may  be  Carried 139 

39.  Effect  of  Train's  Motion  on  the  Distance  from  the  Centre  of  the 

Track  at  which  Sparks  find  Lodgement 141 


TABLE  OF  CONTENTS.  vn 

CHAPTER   VIII. 

CHANCES    OF    FIRE    FROM    SPARKS. 

PAGE 

40.  A  Review  of  Certain  Facts  already  Presented 145 

41.  The  Influence  of  Air-currents  about  a  Moving  Train 148 

42.  Sparks  from  a  Locomotive  and  Sparks  from  a  Fixed  Fire  are  not 

Subjected  to  the  Same  Influences 150 

APPENDIX. 

THE    PURDUE    UNIVERSITY    LOCOMOTIVE    TESTING-PLANT. 

43.  Development  of  the  Plant 153 

44.  The  Wheel-foundation 155 

45.  The  Traction  Dynamometer 159 

46.  The  Superstructure 160 

47.  The  Building 163 


LOCOMOTIVE  SPARKS. 


CHAPTER    I. 

THE   LOCOMOTIVE. 
t 

i.  Fundamental  Conceptions. —The  boiler  and  engine  of 
a  locomotive  are  similar  in  their  general  character  to  the  boiler 
and  engine  which  go  to  make  up  a  stationary  power-plant. 
Each  exists  for  the  purpose  of  converting  into  work  the  poten- 
tial energy  of  fuel.  There  are  differences  in  the  details  of 
mechanism,  and  in  the  conditions  under  which  work  is  per- 
formed, but  the  principles  underlying  action  are  the  same. 

As  compared  with  the  locomotive,  the  stationary  plant  has 
an  advantage  in  being  fixed  in  its  position.  It  may  be  so 
arranged  that  all  its  parts  are  accessible  to  attendants,  who  in 
doing  their  work  may  pass  freely  from  one  element  to  another," 
and  any  detail  which  is  better  when  made  large  can  be  given 
such  dimensions  as  will  insure  its  efficient  and  otherwise  satis- 
factory performance.  In  many  cases  there  are  no  limiting 
dimensions ;  the  plant  may  be  built  as  long  and  as  wide  and  as 
high  as  may  be  desired.  It  is  possible,  therefore,  to  so  con- 
struct the  engines,  boilers,  and  accessory  apparatus  which  go 
to  make  up  a  stationary  plant,  as  to  secure  any  desired  degree 


2  LOCOMOTIVE  SPARKS. 

of  efficiency,  within  limits  which  are  prescribed  by  the  state 
of  the  art.  If  the  pulsating  sound  of  escaping  steam  is  objec- 
tionable, it  can  be  entirely  eliminated  by  the  application  of  a 
suitable  exhaust-head  or  muffler.  If  the  presence  of  a  cloud 
of  exhaust-steam  is  annoying,  it  may  be  entirely  suppressed 
by  the  use  of  a  condenser.  If  smoke  emerging  from  the  top 
of  the  stack  becomes  a  nuisance,  it  may  be  made  to  disappear 
by  the  use  of  down-draft  furnaces,  or  by  the  application  of 
some  other  form  of  so-called  smoke-consumer.  If  economy 
in  the  use  of  fuel  is  an  important  consideration,  small  and 
overworked  boilers  may  be  made  to  give  way  to  others  which 
provide  a  more  liberal  allowance  of  heating-surface.  Engines 
having  atmospheric  exhaust  may  give  way  to  condensing 
engines,  simple  engines  to  compounds,  and  compounds  to 
triple-expansions.  The  degree  of  perfection  which  may  be 
obtained  in  any  or  all  of  these  particulars  is  in  fact  a  matter 
which  is  entirely  within  the  choice  of  the  designer,  subject  only 
to  such  limitations  as  to  cost  as  may  be  imposed  by  business 
considerations. 

In  passing  from  stationary  power-plants  to  moving  power- 
plants  in  the  form  of  locomotives,  the  designer  gives  up  his 
freedom  of  choice  with  reference  to  many  matters  of  detail, 
and  finds  himself  confronted  with  the  necessity  of  having  his 
work  conform  to  certain  general  conditions.  The  work 
which  his  boiler  and  engine  are  to  do  must  be  made  to  appear 
in  the  motion  of  the  plant  itself  and  its  attached  train.  The 
fact  that  the  whole  plant  must  move  across  the  country  with  a 
velocity  equal  to  that  attained  by  the  periphery  of  the  stationary 
engine's  fly-wheel,  requires  the  adoption  of  a  cycle  which  shall 
serve  to  transfer  the  heat-energy  of  the  fuel  into  work,  by  as 
direct  a  process  as  practicable. 

The  stationary  plant  runs  at  a  fixed  speed  and  usually  at  a 


. 


THE  LOCOMOTIVE.  3 

fairly  constant  load ;  the  locomotive  must  run  at  all  speeds ;  it 
must  climb  hills,  pulling  slowly  and  hard,  and  it  must  roll 
rapidly  into  valleys,  holding  back  a  train  which  would  push  it 
on  at  still  higher  speeds. 

Important  elements  must  be  adapted  one  to  another,  and 
there  must  be  an  entire  omission  of  many  details  which  in  good 
practice  are  considered  necessary  to  the  economical  working 
of  a  stationary  plant.  The  moving  parts  of  a  stationary  engine 
work  in  a  substantial  frame,  which  in  turn  is  bolted  to  a  massive 
foundation,  while  the  frame  of  a  locomotive  is  suspended  by 
springs  from  axles  carried  by  wheels  which  are  supported  by 
a  yielding  and  uneven  track.  The  action  of  the  stationary 
engine  can  be  one  of  precision,  and  delicate  and  precise  devices 
may  be  embodied  in  its  mechanism  which  are  not  at  all 
admissible  in  the  less  rigid  structure  of  the  locomotive.  The 
stationary  engine  is  protected  from  the  weather  and  from  dust, 
while  the  locomotive  must  give  no  trouble  if  worked  in  rain  or 
snow,  or  in  clouds  of  dust. 

The  designer  of  a  locomotive,  moreover,  is  forced  to  recog- 
nize that  the  machine  with  which  he  is  concerned  constitutes 
but  one  of  many  elements  which  go  to  make  up  the  material 
property  of  a  railroad.  The  width  between  the  wheels  of  his 
engine  is  prescribed  by  the  gage  of  the  track,  and  the  length 
of  its  wheel-base  by  the  curvature  of  track,  the  length  of  turn- 
tables, and  the  dimensions  of  other  facilities  at  the  terminals 
of  the  road.  The  extreme  width  and  height  of  the  machine 
must  come  within  the  limits  of  clearance  which  are  allowed  on 
either  side  and  above  the  track,  for  the  locomotive  which  he 
designs  must  pass  station-platforms,  underneath  bridges,  and 
through  tunnels. 

With  such  limiting  conditions  as  have  been  indicated,  the 
locomotive  designer  has  for  many  years  been  under  the  neces- 


4  LOCOMOTIVE  SPARKS. 

sity  of  producing  locomotives  which  will  carry  greater  loads 
and  move  at  higher  speeds  than  those  which  have  preceded 
them.  Locomotives  which  could  carry  twenty  cars  have  given 
way  to  newer  and  larger  machines  which  are  capable  of  carry- 
ing forty  cars,  and  trains  which  used  to  be  pulled  at  a  speed  of 
twenty-five  miles  an  hour  must  now  be  carried  at  fifty  miles 
an  hour. 

With  restraining  conditions  fixing  limits  which  are  absolute, 
and  acting  under  the  influence  of  a  growing  demand  for 
increased  power,  it  has  been  necessary  for  the  locomotive 
designer  to  consider  economy  in  the  use  of  fuel  as  a  matter  of 
secondary  importance.  The  problems  of  reducing  noise  and  of 
abating  smoke  have  received  such  attention  as  the  conditions 
have  allowed,  but  each  proposition  dealing  with  these  purely 
secondary  questions  has  of  necessity  been  weighed  by  him 
with  reference  to  their  effect  on  the  output  of  power.  He 
knows  that  smoke  from  a  locomotive  can  be  suppressed,  but 
he  also  knows  that  in  accomplishing  this  the  firing  will  be 
interfered  with  and  the  power  of  the  locomotive  will  be 
reduced.  It  is  to  be  noted,  also,  that  the  need  for  power  is 
not  one  which  he  has  artificially  created,  but  is  the  outgrowth 
of  a  public  demand  for  service.  There  is  in  fact  no  serious 
defect  in  the  working  of  the  modern  locomotive  that  is  not 
understood  and  appreciated  by  the  locomotive  designer.  He 
allows  them  to  exist  because  all  efforts  to  overcome  them 
appear  to  work  to  the  disadvantage  of  more  important  charac- 
teristics of  his  machine. 

It  is  but  just  to  add  that  present-day  designers  of  locomo- 
tives have  not  rested  on  the  achievements  of  their  predecessors 
but  have  added  thereto  a  full  measure  of  their  own  indi- 
viduality. 

The  significance  of  their  achievements    is    to  be   seen    in 


THE  LOCOMOTIVE. 


SCALE  IN  FEET 
0        5        10      IS       20      26 


TWO,  500.   H.   P. 
ENGINES 


FIG.  i. 


6  LOCOMOTIVE  SPARKS. 

Fig.  i,*  which  shows  two  power-plants,  each  of  a  thousand 
horse-power.  Both  are  drawn  to  the  same  scale,  so  that  a 
comparison  of  the  figures  discloses  their  relative  dimensions. 

The  smaller  of  the  two  drawings  represents  a  modern  loco- 
motive having  2500  feet  of  heating-surface  and  20"  X  24" 
cylinders,  and  consequently  quite  capable  of  delivering  the 
power  assigned  it.  The  stationary  plant  represented  by  the 
larger  drawing  is  not  more  liberal  in  its  dimensions  than  such 
plants  have  need  to  be.  It  is  made  up  of  a  suitable  building 
containing  a  battery  of  boilers  and  two  slow-speed  engines  of 
500  horse-power  each. 

The  drawings  tell  their  own  story.  Those  of  the  stationary 
plant  cover  an  area  of  paper  which  is  many  times  greater  than 
that  covered  by  the  drawings  of  the  locomotive  and  yet  the 
power  capabilities  of  the  two  plants  are  the  same.  It  is  evident 
that  a  process  which  permits  the  smaller  apparatus  to  equal 
that  of  the  larger  must  be  one  of  unusual  activity. 

When  one  is  inclined  to  criticize  the  locomotive  because  it 
is  somewhat  less  economical  in  fuel  than  the  stationary  plant, 
or  because  it  sometimes  smokes  a  little  or  sends  out  a  few 
sparks,  he  should  look  at  these  drawings  for  he  will  find  in 
them  a  ready  explanation  and  excuse. 

*  From  the  Railroad  Gazette,  July  20,  1900. 


CHAPTER    II. 

CONDITIONS   CONTROLLING   FURNACE-ACTION   IN  A 
LOCOMOTIVE. 

2.  The  Locomotive-furnace. — A  vertical  section  of  a  loco- 
motive-boiler is  shown  by  Fig.  2.  The  drawing  is  to  be 
considered  somewhat  diagrammatical  since  it  does  not  include 
minor  details. 

The  furnace  or  fire-box,  as  it  is  often  called,  is  at  A.  It 
consists  of  a  chamber  of  steel  surrounded  at  the  top  and  on  the 
sides  by  the  water  of  the  boiler.  The  bottom  of  the  furnace 
is  fitted  with  a  suitable  fire-grate  upon  which  fuel  is  burned. 
An  opening  at  the  back  serves  as  a  fire-door.  Below  the  grate 
there  is  ordinarily  a  sheet-iron  ash-pan  but  this  does  not  appear 
in  the  drawing. 

The  front  sheet  of  the  fire-box,  known  as  the  tube-sheet, 
receives  the  end  of  tubes  which  usually  are  2  inches  in  diameter 
and  which  extend  to  the  front  head  of  the  boiler,  C.  The 
exterior  surfaces  of  the  tubes  are  in  contact  with  the  water  of 
the  boiler  while  their  interior  surface  constitutes  a  way  of 
escape  for  the  furnace-gases.  All  the  products  of  combustion 
resulting  from  the  furnace-action  pass  from  the  furnace  through 
the  tubes  into  the  front-end  or  smoke-box,  D.  In  passing 
the  tubes  the  gases  from  the  furnace  give  up  much  of  their  heat 
to  the  surrounding  water,  the  tube-surface  constituting  a  very 
large  fraction  of  the  entire  heating-surface  of  the  boiler.  From 
the  front-end,  D,  the  gases  from  the  furnace  intermingle  with 

7 


LOCOMOTIVE  SPARKS. 


CONDITIONS   CONTROLLING  FURNACE-ACTION.  9 

the  exhaust-steam  escaping  from  the  pipe  E,  and  are  forced  up 
the  stack  and  out  into  the  atmosphere.  When  the  engine  is 
working  there  is  a  constant  movement  of  air  and  heated  gases 
from  the  grate  into  the  furnace,  through  the  tubes,  into  the 
front-end,  and  up  the  stack. 

3.  Rates  of  Combustion  in  the  Furnace  of  Locomotives. 
— It  has  already  been  shown  that  the  locomotive  is  a  small 
machine,  when  measured  by  the  amount  of  work  demanded  of 
it,  and  it  follows  that  some  or  all  of  its  parts  are  worked  to  a 
higher  pitch  than  the  similar  parts  of  plants  which  have  more 
liberal  dimensions.  This  statement  is  especially  true  in  its 
application  to  the  locomotive  fire-box,  for  the  power  developed 
by  locomotives  is  derived  from  the  fuel  it  burns,  and,  other 
things  being  equal,  whatever  operates  to  increase  the  amount 
of  coal  consumed  contributes  to  an  increase  of  power.  With 
a  steady  growth  in  the  size  of  locomotives,  there  has  been  a 
corresponding  increase  in  the  amount  of  coal  to  be  handled, 
until  now  it  is  not  uncommon  for  a  modern  engine  to  require 
as  much  as  5000  pounds  or  more  for  each  hour  it  runs,  or  83 
pounds  a  minute.  Coal  thus  required  is  burned  in  a  fire-box, 
the  dimensions  of  which  are  limited  by  the  general  arrange- 
ment of  other  important  parts  of  the  machine.  With  large 
quantities  of  coal  to  be  burned,  in  a  furnace  of  small  dimen- 
sions, the  process  of  combustion  is  of  necessity  an  active  one, 
as  will  be  seen  by  the  following  comparisons. 

Soft  coal  upon  a  grate  in  the  open  air  will  burn  at  about 
the  rate  of  3  pounds  an  hour  for  each  square  foot  of  grate-sur- 
face. In  a  heating-stove,  under  usual  conditions  of  draft,  there 
will  be  burned  about  5  pounds  for  each  foot  of  grate,  and  under 
a  stationary  boiler  connected  with  a  good  stack,  the  rate  may 
increase  to  10  or  even  to  20  pounds  per  foot  of  grate.  Again, 
in  naval  practice  with  a  closed  stack-hole  and  draft  forced  by 


io  '  LOCOMOTIVE  SPARKS. 

blowers,  the  rate  of  combustion  is  occasionally  carried  as  high 
as  50  pounds  per  foot  of  grate  per  hour,  but  this  value  may  be 
accepted  as  the  maximum  rate  at  which  fuel  is  burned  for  the 
purpose  of  generating  steam,  except  in  locomotives.  Under 
the  lightest  service  incident  to  common  practice  in  the  narrow 
fire-boxes  of  locomotives,  the  rate  is  between  50  and  100 
pounds,  and  good  practice  allows  it  to  rise  above  150  pounds, 
or  to  three  times  the  rate  attained  under  the  conditions  of 
forced  draft  in  naval  service.  Nowhere  are  fires  urged  with 
greater  intensity  except  in  forges  or  in  furnaces  employed  for 
metallurgical  purposes. 

Stating  the  same  fact  from  a  different  point  of  view,  it  may 
be  said  that  the  grate  of  a  modern  locomotive  has  an  area 
equal  to  that  of  a  small-sized  dining-table.  The  amount  of 
coal  burned  on  it  is  so  large  that  if  burned  in  the  open  air  in 
the  form  of  a  bonfire  it  could  only  be  consumed  by  making 
the  fire  cover  an  area  of  a  thousand  square  feet  or,  say,  a  grate 
io  feet  wide  and  100  feet  long. 

4.  Rates  of  Combustion  and  Grate-areas. — The  preceding 
general  statements  concerning  rates  of  combustion  in  locomo- 
tive-furnaces may  be  accepted  as  fairly  representative  of  condi- 
tions prevailing  in  good  American  practice.  In  order  that  a 
fuller  view  may  be  had  of  the  subject,  it  will  be  well  to 
consider  for  a  moment  what  are  the  conditions  governing  the 
rates  of  combustion,  and  the  expedients  which  have  been 
resorted  to  by  the  American  designer  in  his  efforts  to  keep 
them  within  reasonable  limits. 

As  already  indicated,  the  intensity  of  the  burning  is  well 
expressed  by  the  pounds  of  coal  consumed  per  unit  area  of 
grate.  When  20  pounds  of  coal  are  burned  per  foot  of  grate- 
surface  each  hour,  the  process  of  combustion  is  double  in  its 
intensity  that  which  attends  the  burning  of  io  pounds  on  the 


CONDITIONS   CONTROLLING  FURNACE-ACTION.  ir 

same  area  in  the  same  time.  It  is  evident,  also,  that  with  a 
given  total  weight  of  coal  to  be  burned,  the  rate  of  combustion 
will  be  inversely  proportional  to  the  area  of  the  grate;  that 
is,  as  the  grate  is  increased  in  size,  the  rate  of  combustion 
will  be  diminished.  In  their  desire  to  keep  the  rate  of 
combustion  within  reasonable  limits,  locomotive  designers 
have  continually  sought  means  whereby  the  grate  might  be 
enlarged. 

Previous  to  1 890  practically  all  American  locomotives  were 
built  along  the  same  general  lines  The  fire-box  extended 
down  between  the  side-frames,  while  the  axle  of  the  forward 
drivers  passed  across  in  front  and  that  of  the  rear  drivers  behind. 
Under  these  conditions,  the  maximum  width  of  the  grate  was 
between  34  and  35  inches.  It  could  not  be  made 'materially 
greater  without  widening  the  gage  of  the  track.  The  length 
of  the  grate  was  determined  by  the  spacing  of  the  two  axles 
already  referred  to,  and  which  were  ordinarily  8  feet  apart,  the 
feeling  being  that  the  coupling-rods  by  which  the  drivers  of 
each  side  are  connected,  one  with  another,  should  not  be 
longer  than  was  necessary  to  span  this  distance.  With  these 
limitations,  after  allowing  clearance  for  axles  and  eccentrics, 
the  maximum  length  of  the  grate  could  be  about  75  inches. 
A  width  of  35  inches  and  a  length  of  75  inches  gives  an  area 
of  about  1 8  feet.  For  a  time  it  appeared  that  this  must  remain 
the  maximum  size  of  grate.  Gradually,  however,  side-rods 
were  lengthend  to  8J  and  even  9  feet,  with  a  corresponding 
gain  in  length  of  grate.  At  the  same  time,  also,  there  began 
the  practice  of  sloping  the  grate  and  raising  the  centre  line  of 
the  whole  boiler.  By  these  means  the  back  of  the  grate  was 
brought  sufficiently  high  to  pass  over  the  rear  axles,  permitting 
the  fire-box  to  extend  rearward  an  indefinite  distance.  The 
practical  limit  to  the  length  of  grate  under  these  conditions 


12  LOCOMOTIVE  SPARKS. 

was,  however,  found  to  be  the  distance  from  the  fire-door  at 
which  a  fireman  could  spread  coal  over  the  forward  end  of  the 
grate — a  distance  which  could  not  be  allowed  to  exceed  10 
feet;  and  in  many  cases  the  maximum  length  was  fixed  at 
9  feet.  By  these  means  the  grate-area  was  made  to  approach 
30  square  feet. 

The  next  great  step  was  taken  when  the  boiler  was  still 
further  raised,  the  depth  of  the  fire-box  diminished,  and  the 
form  of  the  frame  modified  so  that  the  fire-box  could  rest  on 
top  of  the  frames  instead  of  extending  between  them.  This 
enabled  the  width  of  the  grate  to  be  increased  by  an  amount 
equal  to  the  sum  of  the  width  of  the  two  side-frames  which  is 
from  8  to  10  inches.  This  change  permitted  an  extension  of 
grate-area  to  about  36  feet  but  in  the  case  of  the  eight-wheeled 
type  of  engine  no  further  increase  of  area  can  be  had  by 
widening  the  fire-box  which  must  still  come  between  the 
drivers. 

Further  extensions  in  grate-area  can,  however,  be  had  by 
the  adoption  of  such  a  modification  in  wheel  arrangement  as 
will  permit  the  fire-box  to  be  extended  sidewise  beyond  the 
gage  of  the  track.  Such  exceptional  designs  have  from  time 
to  time  appeared,  the  most  noteworthy  being  the  Wootten 
boiler,  having  a  shallow  fire-box  extending  out  over  the 
wheels,  giving  an  area  of  from  60  to  85  square  feet.  To  allow 
the  use  of  so  wide  a  structure,  the  coupled  drivers  are  brought 
close  together  and  placed  ahead  of  the  fire-box,  the  rear  of  the 
engine  being  carried  on  a  pair  of  small  trailing  wheels,  over 
the  top  of  which  the  fire-box  is  free  to  extend.  Locomotives 
having  such  a  wheel  arrangement  have  come  to  be  known  as 
of  the  Atlantic  type. 

The  Wootten  boiler  was  originally  designed  for  burning  fine 
anthracite  coal  which  needs  to  be  spread  very  thin  and  per- 


CONDITIONS   CONTROLLING   FURNACE-ACTION.  13 

mitted  to  burn  at  a  comparatively  low  rate.  As  the  supply  of 
such  coal  is  not  general,  these  engines  have  been  confined  to 
a  limited  area  within  which  the  fine  anthracite  coal  is  to  be 
had.  It  is  to  be  noted  that  the  Atlantic  type  of  engine  is  not 
adapted  to  all  classes  of  service;  also,  that  the  Wootten  boiler 
is  serviceable  only  in  connection  with  the  peculiar  fuel  which 
it  is  designed  to  use.  When  tried  with  a  lighter  bituminous 
coal,  such  as  must  be  used  in  our  Western  States,  it  was  found 
impossible  for  a  single  fireman  to  keep  the  grate  covered,  with 
the  result  that  steam-pressure  could  not  be  maintained.  The 
fact  to  be  emphasized  is  that  the  existence  of  the  Wootten 
boiler  is  not  in  itself  evidence  that  rates  of  combustion  in  all 
locomotives  using  all  classes  of  fuel  can  be  made  low. 

There  are  now,  in  1900,  evidences  that  the  essential 
features  of  the  Atlantic  type  engine  and  of  a  modified  form  of 
the  Wootten  boiler  will  be  adopted  in  locomotives  designed 
for  burning  soft  coal.  Several  roads  of  the  Middle  and 
Western  States  now  have  wide  fire-boxes  in  service  which 
have  from  40  to  50  feet  of  grate-area.  This  is  as  large  a  grate- 
area  as  can  well  be  fired  with  soft  coal  by  one  man. 

In  spite  of  the  gradual  increase  in  grate-area  which  has 
been  noted,  rates  of  combustion  per  unit  of  grate-area  have 
not  greatly  declined  in  recent  years.  Such  progress  as  may 
have  been  made  in  securing  enlarged  grates  has  done  but  little 
more  than  to  keep  pace  with  the  increased  amounts  of  fuel 
which,  as  engines  have  increased  in  power,  are  required  to  be 
burned.  What  this  rate  is  required  to  be  for  the  development 
of  varying  amounts  of  power  is  well  shown  by  results  obtained 
in  a  series  of  tests  made  upon  the  Purdue  experimental  locomo- 
tive (see  Appendix).  This  locomotive  is  now  to  be  regarded 
as  one  of  rather  small  size.  It  weighs  85,000  pounds,  has 
17"  X  24''  cylinders  and  during  the  tests  was  run  at  a  speed 


14  LOCOMOTIVE  SPARKS. 

of  35  miles  an  hour  with  a  wide-open  throttle  and  a  steam- 
pressure  of  130  pounds,  conditions  and  results  as  to  coal 
burned,  all  of  which  may  be  accepted  as  within  the  limits  of 
good  practice,  being  as  follows: 

Tut  off  Hnrcp  nnw*»r         Total  Pounds        Coal  per  Sq.  Ft. 

rer'      Coal  per  Hour,      of  Grate  per  hour. 

6"  300  1262  72 

8"  434  1978  113 

10.5"  495  3133  179 

5.  Draft. — The  passage  of  air  through  a  mass  of  burning 
fuel  constitutes  what  is  usually  known  as  "draft."  It  is  by 
the  action  of  the  draft  that  the  process  of  combustion  is  stimu- 
lated. If  the  draft  is  weak,  the  rate  of  combustion  is  low;  if 
strong,  the  rate  of  combustion  becomes  high.  The  draft  is, 
in  fact,  in  all  cases  the  regulator  by  means  of  which  the  rate 
of  combustion  is  controlled.  It  has  already  been  shown  that 
the  rate  of  combustion  in  a  locomotive  is  abnormally  high  and 
it  follows  that  the  draft  must  be  correspondingly  strong. 

In  a  locomotive  the  draft  results  from  the  action  of  the 
exhaust-steam  which,  after  doing  its  work  in  the  cylinders  of 
the  engine,  is  made  to  pass  upward  through  the  smoke-box 
and  out  by  the  stack  in  such  a  manner  and  at  such  velocity  as 
will  induce  a  current  in  the  smoke-box  gases  through  which  it 
passes.  In  this  manner  the  exhaust-jet  serves  not  only  to 
discharge  the  smoke-box  gases,  but  it  draws  upon  them  with 
sufficient  vigor  to  produce  a  partial  vacuum  in  the  front-end. 
This  condition  prevails  whenever  the  engine  is  in  action. 

With  a  pressure  in  the  front-end  which  is  less  than  that  of 
the  atmosphere,  there  is  a  constant  tendency  for  air  to  pass 
from  the  atmosphere  to  the  front-end.  The  only  avenue  is  by 
way  of  the  ash-pan  through  the  burning  fuel,  into  the  furnace, 
and  thence  on  through  the  tubes.  The  activity  of  this  move- 


CONDITIONS   CONTROLLING  FURNACE-ACTION. 


ment  will  evidently  depend  upon  the  difference  between  the 
atmospheric  pressure  and  the  pressure  in  the  front-end,  and  it 
has  become  the  practice  to  measure  the  intensity  of  the  draft- 
action  in  terms  of  this  difference  of  pressure.  The  unit  of 
measure  is  usually  taken  to  be  the  displacement  of  a  column 
of  water  I  inch  high,  equivalent  to  0.04  pound  per  square  inch, 
or  5.2  pounds  per  square  foot.  The  draft  employed  in  boilers 
of  stationary  plants  with  good  stacks  is  from  o.  I  to  1.4  inches 
of  water.  In  naval  practice,  with  closed  stack-hole  and  forced 
draft,  it  is  from  I  to  4  inches,  while  in  a  locomotive  burning 
bituminous  coal,  it  ranges  from  3  to  10  inches,  depending  upon 
the  service,  character  of  the  fuel,  and  the  condition  of  the  fire. 
Under  ordinary  conditions  of  service  it  does  not  often  fall 
below  6  inches,  which  is  equivalent  to  a  difference  of  pressure 
between  that  of  the  atmosphere  and  that  of  the  gases  of  the 
front-end  of  31  pounds  per  square  foot.  Such  a  draft  is  quite 
comparable  in  intensity  with  that  employed  to  urge  the  fire  of 
a  blacksmith's  forge,  though  in  the  latter  case  the  area  affected 
is  small,  while  in  the  former  case,  the  full  area  of  the  grate  is 
affected.  The  relation  between  draft  and  rate  of  combustion 
for  the  experimental  locomotive  of  Purdue  University  is  as 
follows: 


Reduction  of  Pressure  in  Front-end  as 
Compared  with  Pressure  of  Atmosphere. 

Pounds  of  Coal  per  Square  Foot  of  Grate 
per  Hour. 

Inches  of  Water. 

Pounds  per  Sq.  Ft. 

Brazil  (Ind.)  Block. 

New  River. 

2.OO 

3-34 
4-30 

10.40 

17-37 
22.36 

64.14 
II3-46 
146.62 

53-oo 
81.00 

IOO.OO 

CHAPTER    III. 
CINDERS   AND   SPARKS. 

6,  How  Cinders  are  Made. — The  activity  which  charac- 
terizes the  process  that  goes  on  in  the  fire-box  of  locomotives 
has  already  been  described.  That  required  rates  of  combustion 
may  be  maintained,  the  air-currents  passing-  through  the  fire 
need  to  be  very  strong.  Air  enters  through  the  grate,  mingles 
for  an  instant  with  the  combustible  properties  of  the  fuel,  the 
fuel  burns,  and  the  products  of  combustion  are  as  quickly 
drawn  away  from  the  fire-box,  through  the  tubes  to  the  front 
end,  and  thence  forced  up  the  stack  and  into  the  atmosphere. 
The  whole  passage  from  the  grate,  through  the  fire-box,  and 
into  the  tubes  is  as  in  a  twinkle  of  an  eye. 

The  layer  of  incandescent  fuel  often  dances  on  the  in-rush- 
ing currents  of  air  and  if  by  chance  some  portions  become 
thinner  than  others,  individual  coals  of  considerable  size  are 
tossed  far  above  the  general  level  of  the  fire,  settling  back  and 
awaiting  for  an  instant  a  new  impulse  to  send  them  up  again, 
responding  to  the  action  of  'the  exhaust,  just  as  apples  keep  in 
air  in  response  to  the  toss  of  a  boy's  hand.  If  the  spot  con- 
tinues to  become  thinner,  the  strength  of  the  draft  will  after  a 
time  overcome  the  weight  of  the  fuel,  which  floats  away  bodily, 
leaving  a  <(  hole  "  in  the  fire  with  the  bare  grate  at  the  bottom. 

In  the  midst  of  such  conditions  as  these,  sparks  are  born. 
Light  particles  of  coal,  unless  well  cemented  together  by 

water  when  thrown  into  the  furnace,  never  reach  the  grate  but 

16 


CINDERS  AND  SPARKS.  if 

ignite  in  the  flame  of  the  furnace  and  partially  consumed  are 
borne  into  the  tubes.  When  a  friable  coal  is  used,  the  lumps 
on  the  grate,  breaking  up  under  the  action  of  heat,  give  rise 
to  many  small  fragments  which  prove  too  light  to  keep  their 
place  with  the  more  solid  masses  of  the  fire.  These  also  fly 
into  the  tubes.  Much  of  the  ash  which  results  from  the  com- 
bustion of  fuel  on  the  grate,  and  which  in  a  stationary  boiler 
would  drop  through  to  the  ash-pan  is,  in  a  locomotive-boiler, 
caught  up  by  the  draft  and  carried  into  the  tubes  along  with 
the  incandescent  coke  to  which  reference  has  already  been 
made.  It  is  in  this  manner  that  the  procession  of  cinders  is. 
formed.  Every  particle  which  enters  the  tubes  at  the  fire-box 
end  is  ordinarily  carried  through  into  the  smoke-box.  Here 
some  are  entrapped.  In  the  smoke-box  they  gradually  cool, 
the  exclusion  of  outside  air  preventing  the  combustible  portion 
from  burning.  At  the  end  of  the  run  they  are  removed.  The 
remainder,  after  being  baffled  and  knocked  about  by  obstacles 
set  in  their  path,  and  greatly  lowered  in  temperature  by  con- 
tact with  escaping  steam,  are  thrown  out  from  the  top  of  the 
stack. 

7.  Front-end  Cinders. — It  will  be  seen  that  the  solid 
material  entering  the  tubes  from  the  fire-box  has  either  the 
form  of  living  coal  or  that  of  ash.  By  the  time  it  reaches  the 
front-end  the  coal  has  become  coke.  The  mixture  of  finely 
divided  coke  and  ash  which  finds  its  way  into  the  smoke-box 
is  indiscriminately  referred  to  as  sparks,  cinders,  smoke-box 
cinders,  and  front-end  cinders,  these  terms  applying  to  the 
material  while  it  is  within  the  front-end  and,  also,  after  it  is 
removed  therefrom  and  put  to  various  uses.  Without  attempt- 
ing to  discuss  the  reason  underlying  the  use  of  these  various 
terms,  that  of  ' '  front-end  cinders  ' '  will  be  employed  for  the 
purpose  of  the  present  text. 


1 8  LOCOMOTIVE  SPARKS. 

8.  Sparks. — Of  all  the  solid  particles  which  pass  through 
the  tubes  and  which  by  convention  are  to  be  called  front-end 
cinders,  a  portion  passes  out  of  the  top  of  the  stack.      Such 
particles  are  commonly  spoken  of  as  "  sparks  "  or  "  cinders." 
For  the  present  purpose  they  will  be  called  sparks.      It  should 
be  noted  that  this  term  is  adopted  merely  as  a  definition ;  it  is 
not  strictly  descriptive.      The  cinders  which  escape  from  the 
front-end  and  become  sparks  retain  all  the  characteristics  of 
front-end    cinders.       Some    are    composed     entirely    of  ash. 
Others  are  of  coke  which,  in  their  passage  of  the  front-end, 
have  been  hammered  against  plates  and  immersed  in  steam 
until  they  are  entirely  deprived  of  fire,  and  are  as  incapable  of 
doing  damage  by  fire  as  the  ash  itself.      All  such  sparks  are 
commonly  referred  to  as  "  dead  sparks. ' '      Still  others,  con- 
stituting  a  very  small   proportion  of  the  whole,   escape  at   a 
temperature  sufficiently  high  to  glow  in  the  dark,  and  of  these 
it  sometimes  happens,  where  very  light  fuel  is  used,  that  a  few 
flame.      But  flaming  sparks  are  of  rare  occurrence. 

9.  The  Conditions  Affecting  the  Production   of  Cinders 
and  Sparks. — The  production  of  front-end  cinders  and  sparks 
depends  upon  many  variable  factors.      As  has  been  shown,  the 
most  active  agent  is  to  be  found  in  the  action  of  the  draft,  but 
the  condition  of  the  fire,  manner  of  firing,  and  the  character  of 
the    fuel,   all    have    their    influence.      Fine  coal,   if  fired   dry, 
results   in   more   cinders   and   sparks   than  when  well  wetted 
before  firing.      A  light  friable  coal,  even  though  thrown  upon 
the  grate  in  large-sized  lumps,  will  often,  under  the  action  of 
heat,  quickly  break  into  smaller  fragments,  many  of  which  are 
sufficiently   small    to    be   caught   up   by  the   draft.      A    good 
quality  of  bituminous  coal  which  holds  together  well  in  burning 
will  give  off  very  few  live  sparks,  and  the  sparks  of  anthracite 
coal  are  practically  nothing  but  ash. 


CINDERS  AND  SPARKS.  19 

It  will  be  evident  that  conditions  favorable  to  the  produc- 
tion of  cinders  and  sparks  are,  under  normal  conditions  of 
working,  always  present ;  that  this  fact  is  not  the  outcome  of 
improper  design  nor  of  any  failure  to  appreciate  the  disadvan- 
tages they  involve  on  the  part  of  those  responsible  for  the 
proper  operation  of  locomotives ;  but  they  exist  as  a  necessary 
consequence  of  the  exactions  of  service  and  in  spite  of  the 
efforts  of  skillful  men  who  have  lived  and  worked  since  the  day 
of  Stephenson  to  overcome  them. 

10.  Experiments  to  Determine  the  Extent  of  Spark- 
losses. — Such  experiments  were  first  made  in  the  laboratory 
of  Purdue  University.  The  locomotive  of  this  laboratory  is  so 
mounted  that  while  its  machinery  may  be  run  at  any  speed  and 


/  /' 

1                          1           "I 

I 

Hi 

=L 

M  —  \— 

1      '_:-.•': 

SLIDING  J 
FRAME 

BUCKET 
ROOF 

LOCOMOTIVE  STACK 

-_ 

FIG.  3. 

under  any  condition  of  load,  the  locomotive  as  a  whole  main- 
tains a  fixed  position.  It  is  possible,  therefore,  in  the  case  of 
this  locomotive  to  work  about  the  top  of  the  stack  in  a  manner 
which  would  be  wholly  inadmissible  in  connection  with  a 
locomotive  on  the  road. 

The  apparatus  employed  in  determining  the  extent  of  spark- 
losses  is  shown  by  Fig  3.*     It  consists  of  an  inverted  U  tube 

*  From  a  paper  on  "  The  Effect  of  High   Rates  of  Combustion  upon  the 
Efficiency  of  Locomotive-boilers." — New  York  Railway  Club,  Sept.,  1896. 


20 


LOCOMOTIVE  SPARKS. 


of  galvanized  iron,  securely  fastened  to  a  movable  frame,  by 
means  of  which  the  tip,  which  constitutes  one  extremity  of  the 
tube,  can  be  projected  across  the  top  of  the  locomotive  smoke- 
stack. The  outer  end  of  the  tube  may  thus  be  made  com- 
pletely to  intercept  a  portion  of  the  stream  issuing  from  the 
stack,  and  the  continuous  action  of  this  stream  is  sufficient  to 
drive  the  intercepted  portion  through  the  tube  and  out  at  the 
other  end.  The  gases  passing  the  tube  bear  the  sparks  on 
their  current,  and  they  are  collected  in  a  bucket  set  to  entrap 
them.  Reference  marks  upon  the  sliding  and  the  fixed  frames 
permit  the  tube  to  be  placed  in  definite  locations  relative  to  the 
centre  of  the  stack.  This  device,  when  in  service,  catches 
everything  excepting  the  lightest  soot,  which  is  allowed  to 
escape  unaccounted  for. 

After  assuming  the  cross-section  of  the  stream  issuing  from 
the  stack  to  be  cut  up,  by  a  series  of  concentric  circles,  into 
one  circular  and  several  annular  areas,  as  shown  by  Fig.  4, 


FIG.  4. 

the  small  end  of  the  U  tube  was  placed  in  the  position  marked 
/and  held  there  for  thirty  minutes,  the  sparks  collected  during 
this  interval  being  credited  to  this  position.  The  tube  was 


CINDERS  AND   SPARKS.  21 

then  moved  to  the  position  //,  where  it  remained  for  another 
period  of  thirty  minutes.  In  like  manner,  it  was  made  to 
occupy,  successively,  the  positions  ///  and  IV,  and  also  the 
positions  7L ,  11^ ,  III^ ,  and  IVl ,  the  weight  of  sparks  caught 
during  each  interval  being  credited  to  the  corresponding  posi- 
tion occupied  by  the  small  end  of  the  tube.  This  end  of  the 
tube  had  an  area  of  I  square  inch,  and  it  was  assumed  that  the 
average  weight  of  sparks  passing  the  tube  while  in  the  positions 
/  and  /j  would  be  the  same  as  that  passing  every  square  inch 
in  the  annular  space  in  which  these  positions  are  located.  For 
example,  the  outer  annular  area,  in  which  /  and  /x  are  located, 
contains  88  square  inches.  If,  in  half  an  hour,  0.5  pound  was 
collected  by  the  tube  in  the  position  /,  and  in  another  half 
hour  0.3  pound  was  collected  from  the  position  7X,  the  sum  of 
these  two  weights,  or  o.  8  pound,  collected  during  a  period  of 
one  hour  would  be  the  average  weight  per  square  inch  per 
hour  collected  from  the  two  positions,  and  the  weight  for  the 
whole  outside  annular  area  would  be  O.8  times  88,  the  number 
of  square  inches,  or  70.4  pounds  per  hour.  A  similar  experi- 
ment and  calculation  gave  the  weight  per  hour  delivered  by 
each  of  the  other  annular  areas  //  and  ///,  and  by  the  circular 
area  IV.  The  sum  of  these  separate  determinations  was 
assumed  to  be  the  total  weight  of  sparks  per  hour  delivered 
from  the  stack. 

ii.  Size  of  Front-end  Cinders  and  of  Sparks. — So  far  as 
mechanical  arrangements  are  concerned,  there  is  nothing  to 
limit  the  size  of  front-end  cinders  except  the  diameter  of  the 
tubes  through  which  they  must  pass.  These  generally  have  a 
clear  diameter  of  about  if  inches.  The  dimensions  of  front- 
end  cinders  cannot  exceed  and  seldom  reach  such  limits.  The 
active  conditions  affecting  their  size  are  to  be  found  in  the 
strength  of  the  draft  and  the  character  of  the  fuel. 


22  LOCOMOTIVE  SPARKS. 

Sparks  discharged  from  the  stack  are  as  a  rule  much 
smaller  than  front-end  cinders.  After  passing  the  tubes  these 
are  met  by  a  complicated  series  of  obstructions  which  serve  to 
break  them  up  and  to  stop  all  which  exceed  certain  fixed 
limits  in  size.  What  these  retarding  agents  are,  it  is  the  prov- 
ince of  another  chapter  to  explain.  In  general,  it  may  be  said 
of  sparks,  as  of  front-end  cinders,  that  their  size  depends  upon 
the  draft  and  the  character  of  the  fuel. 

An  exhibit  of  typical  cinders  and  sparks  is  presented  as 
Figs.  5  and  6.  In  each  case  the  pile  A  is  made  up  of  sparks 
emitted  from  the  top  of  the  stack,  collected  in  the  manner 
already  described,  while  the  pile  B  is  composed  of  cinders 
taken  from  the  front-end  after  a  run.  For  purposes  of  com- 
parison, a  pile  of  buckshot  (C)  is  added,  the  diameter  of  the 
individual  shot  being  T5^  of  an  inch.  •  The  sparks  and  cinders 
making  up  Fig.  5  represent  conditions  of  heavy  running. 
They  were  obtained  during  a  test  for  which  the  draft  was 
represented  by  7  inches  of  water  and  the  rate  of  combustion 
was  221  pounds  of  coal  per  foot  of  grate  per  hour.  Fig.  6 
represents  conditions  of  light  running,  the  materials  shown 
having  been  obtained  during  a  test  for  which  the  draft  was 
represented  by  3  inches  of  water  and  the  rate  of  combustion 
was  84  pounds  of  coal  per  foot  of  grate  per  hour.  The  coal 
was  Brazil  block  and  the  tests  were  made  on  the  experimental 
plant  of  Purdue  University.  The  materials  shown  on  both 
figures  may  be  accepted  as  representative  of  all  that  accumu- 
lated during  tests  of  several  hours'  duration,  and  as  extreme 
conditions  are  represented,  it  is  but  fair  to  presume  that  the 
largest  sparks  which  are  likely  to  be  given  off  from  the  stack 
by  an  engine  in  good  condition  are  those  shown  by  A,  Fig.  5, 
and  that  under  lighter  conditions  of  running  they  may  not  run 
larger  than  those  shown  by  A,  Fig.  6. 


CINDERS  AND  SPARKS.  27 

12.  The  Loss  of  Fuel  by  Cinders  and  Sparks — The  total 
cinder-  and  spark  -loss  for  any  given  period  is  found  by  ascer- 
taining the  weight  of  the  solid  material  which  accumulates  in 
the  front-end  and  the  weight  which  is  discharged  from  the  top 
of  the  stack.  Weighings  of  the  front-end  cinders  are  readily 
made  at  the  end  of  a  run  and  the  weight  of  sparks  passing  out 
of  the  stack  may  be  determined  by  the  method  already 
described. 

Results  of  an  investigation  thus  made  are  presented  in 
Table  I. 

TABLE  I. 

SHOWING  WEIGHT  OF  CINDERS  AND  SPARKS  FROM  THE 
PURDUE  LOCOMOTIVE,  SCHENECTADY  NO.  1,  WHEN 
USING  BRAZIL  BLOCK  COAL. 


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I. 

II. 

III. 

IV. 

V. 

VI. 

VII. 

VIII. 

IX. 

X. 

I 

15 

I 

1-93 

79L5 

45.23 

21.90 

12.30 

34-20 

.043 

2 

35 

I 

2.98 

1464.8 

83.70 

41.20 

63.20 

104.4 

.071 

3 

35 

I 

3-02 

1513.6 

86.50 

46.10 

49.90 

96.00 

.063 

4 

35 

I 

3-oo 

I557.I 

88.98 

45.00 

63-40 

108.4 

.070 

5 

55 

I 

3-57 

1884.4 

107.68 

127.5 

157-2 

284.7 

•151 

6 

35 

3 

4.88 

2017.7 

115.29 

IIO.O 

67.30 

177-3 

.088 

7 

15 

9 

4-99 

2I2I.O 

121.20 

215.5 

78.00 

293-5 

.138 

It  is  to  be  noted  from  the  data  given  in  Table  I  that  the 
draft  conditions  for  the  tests  under  consideration  range  from  2 
to  5  inches  of  water ;  that  the  coal  burned  per  hour  varies  from 


28  LOCOMOTIVE  SP4RKS. 

790  to  2100  pounds,  which  is  equivalent  to  a  rate  per  hour  of 
from  45  to  12  I  pounds  per  foot  of  grate. 

The  weight  of  sparks  passing  up  the  stack,  and  cinders  col- 
lecting in  the  front-end  per  hour,  respectively,  are  given  in 
Columns  VII  and  VIII,  while  the  total  weight  appears  in 
column  IX. 

Column  X  gives  the  ratio  of  total  weight  of  sparks  and 
cinders  to  the  total  weight  of  coal.  It  shows  that  the  losses 
arising  from  this  cause  vary  from  a  little  more  than  4  per  cent 
to  nearly  14  percent  of  the  weight  of  coal  fired,  the  loss  being 
greatest  when  the  rate  of  combustion  is  highest.  The  relation 
between  the  rate  of  combustion,  weight  of  cinders  caught  in 
front-end,  the  weight  of  sparks  passing  out  at  the  stack,  and 
the  total  weight  of  sparks  and  cinders,  is  shown  graphically 
by  Fig.  7,  which  is  plotted  from  the  data  given  in  Table  I. 
The  relation  between  the  weight  of  sparks  passing  out  at  the 
stack  and  the  weight  of  cinders  retained  in  the  front-end  as 
shown  by  these  tests,  is  not  considered  conclusive  since  it  must 
depend  somewhat  on  the  length  of  the  test,  that  is,  upon  the 
frequency  with  which  the  front-end  is  cleaned,  but  the  facts 
are  presented  as  obtained.  It  appears,  however,  that  Test 
No.  I  shows  a  larger  loss  by  the  stack  than  by  the  front-end 
but  the  value  of  the  whole  loss  for  this  test  is  small.  Disre- 
garding this  test,  it  appears  in  general  that  the  spark-losses  as 
compared  with  the  losses  by  cinders  collecting  in  the  front- 
end,  increase  as  the  rate  of  combustion  increases.  Thus  in 
Test  No.  2,  the  stack  losses  are  less  than  half  the  total  loss; 
while  for  Test  No.  7  they  constitute  more  than  two-thirds  the 
total  loss.  The  results  of  Tests,  Nos.  2,  3,  and  4  are  of 
especial  interest,  since  they  were  run  under  conditions  which 
gave  very  nearly  identical  rates  of  combustion  and  served  as  a 
check  one  upon  the  other.  Test  No.  5  shows  a  cinder-loss 


CINDERS  ^ND  SPARKS. 


29 


relatively  higher  than  that  of  either  Tests  Nos.  6  or  7.     This, 
while  unexpected,  may  possibly  be  accounted  for  by  the  fact 


saisinod 


that  this  was  a  high-speed  test.  The  draft  of  3.57  inches  re- 
sulted from  exhaustive  pulsations  so  rapid  as  to  give  great 
steadiness  to  the  outflowing  jet  of  steam. 


3°  LOCOMOTIVE  SPARKS. 

Test  No.  6  should  be  compared  with  Test  No.  3  rather 
than  with  Test  No.  5,  since  Test  No.  3  has  the  same  speed; 
while  Test  No.  5,  as  already  noted,  was  run  with  a  much 
higher  speed.  The  smaller  values  given  for  Test  No.  6,  as 
compared  with  those  derived  from  the  preceding,  if  not  the 
result  of  inaccuracies,  must  be  due  to  the  fact  that  the  cut-off 
for  this  test  was  considerably  increased  as  compared  with  that 
of  all  the  preceding  tests ;  the  result  being  that  while  the  draft 
was  stronger  and  while  more  coal  was  burned,  it  did  not  have 
the  same  effect  upon  the  fire  as  that  produced  by  the  sharper 
and  shorter  blast.  However,  the  data  is  not  sufficient  to  be 
conclusive  upon  this  point. 

Test  No.  7  was  run  under  a  long  cut-off  with  the  throttle 
partly  closed  and  at  a  slow  speed,  the  conditions  being  such 
as  to  give  a  very  strong  exhaust-action.  The  draft  was 
greater  than  for  any  of  the  preceding  tests  and  more  coal  was 
burned  per  unit  of  time.  The  weight  of  cinders  caught  in  the 
front-end  is  not  greatly  in  excess  of  the  weight  of  the  pre- 
ceding tests,  and  is  even  less  than  for  Test  No.  5,  but  the 
weight  of  sparks  passing  out  of  the  stack  is  greater  than  for 
any  other  test;  the  strong  blast  evidently  tending  to  clear  the 
front-end  of  a  portion  of  the  accumulation  which  otherwise 
would  have  lodged  there. 

In  conclusion,  it  should  be  noted  that  the  value  of  the  fuel- 
loss  by  sparks  and  cinders,  while  depending  chiefly  upon  the 
rate  of  combustion,  is  affected  also  by  the  character  of  the 
exhaust  which  in  turn  is  dependent  upon  the  cut-off  and  speed. 
As  these  losses  increase,  the  relative  proportion  of  the  whole 
escaping  by  the  stack  increases ;  a  result  which  may  in  part  be 
due  to  the  limited  capacity  of  the  front-end  and  to  a  more 
perfect  scouring  action  arising  from  the  stronger  currents 
within  it. 


CINDERS  AND  SPARKS. 


As  already  noted,  the  results  thus  far  discussed  were 
obtained  in  connection  with  Brazil  block  coal,  a  coal  which 
being  light  and  rather  friable,  lends  itself  to  the  production  of 
a  rather  high  percentage  of  sparks  and  cinders.  Later  investi- 
gations made  at  Purdue  in  connection  with  five  different 
samples  of  bituminous  coal  submitted  by  the  Big  Four  Rail- 
road gave  results  which  are  of  interest  in  this  connection. 

The  apparatus  used  and  the  methods  employed  were  essen- 
tially the  same  as  those  described  in  the  preceding  test. 

Values  of  the  spark-losses  for  each  of  the  several  samples 
of  coal  tested  are  presented  in  Table  II. 

TABLE  II.* 

SHOWING  WEIGHT  OF  CINDERS  AND  SPARKS  FROM  THE 
PURDUE  LOCOMOTIVE,  SCHENECTADY  NO.  2,  WHEN 
USING  FIVE  DIFFERENT  GRADES  OF  COAL. 


"3. 

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S'Su 

Si' 

"y 

J2 

A       *o 
far. 

umber. 

1 

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a 

0 

ll 

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I 

S 

s 

c   . 

i§ 

0  = 

osition  of  Reverse 
Lever.  Notches 
forward  of  Centn 

CO 

1 

C  u 

otal  Pounds  of  Co 
Fired  per  Hour. 

III 

Ifsg 

ounds  of  Water 
Evaporated  per 
Square  Foot  of  H 
ing  Surface  per  H 

ounds  of  Sparks 
Passing  out  of  St£ 
per  Hour. 

ijj 

otal  Pounds  of 
Cinders  and  Spar 
per  Hour. 

atio  of  Total  Weij 
of  Cinders  and 
Sparks  to  Weight 
Coal  Fired 

fe 

Q 

C/5 

OH 

Q 

H 

cu 

cu 

PH 

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« 

I. 

II. 

III. 

IV. 

V. 

VI. 

VII. 

VIII. 

IX. 

X. 

XI. 

XII. 

i 

E. 

15 

5 

i-5i 

685 

40.30 

4-53 

14.90 

20.97 

35-87 

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2 

E. 

50 

2 

5-13 

2025 

119.1 

IO.O2 

294-5 

174.0 

468.5 

•231 

3 

E. 

30 

8 

5-73 

2161 

127.1 

10.54 

3"-4 

145.8 

457-2 

.211 

4 

D. 

15 

5 

1.70 

905 

53-30 

4.72 

13-5° 

31-86 

45.36 

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5 

D. 

2 

5-4° 

2402 

141-3 

9.82 

289.9 

124.4 

4H-3 

.172 

6 

D. 

30 

8 

6.98 

2880 

169.4 

II.  II 

448.2 

"8.5 

576.7 

.2OO 

7 

C. 

15 

5 

1.77 

983 

57.80 

4.91 

12.50 

16.98 

29.48 

.030 

8 

C. 

50 

2 

5-34 

2403 

141-3 

9-95 

198.7 

127.3 

326.5 

.136 

9 

C. 

30 

8 

5-74 

2606 

153-3 

10.24 

253-4 

124.6 

378.0 

-145 

10 

A. 

15 

5 

1.70 

782 

46.00 

4.78 

16.20 

28.40 

44.60 

•°57 

ii 

A. 

5° 

2 

5-67 

2045 

120.3 

9.87 

208.6 

I2O.O 

328.6 

.l6l 

12 

A. 

8 

6.32 

2364 

J39-' 

iQ-34 

208.9 

149.6 

358.5 

.151 

13 

B. 
B. 

15 

So 

5 

2 

1.89 
5.67 

831 
2235 

48.90 
132.0 

4.76 
9-90 

10.60 
236.1 

24-95 
126.4 

362.5 

.040 
.162 

'5 

B. 

3° 

8 

6.40 

2491 

146.5 

10.70 

3I3-8 

133-4 

447.2 

.ISO 

*  Compiled  from  a  paper  on  "  Tests  of  Coal  for  Locomotives,"  by  William  Garstang,  Supt. 
of  Motive  Power  C.  C.  C.  &  St.  L.  R.  R.     Proceedings  of  Western  Railway  Club,  Dec.  »$» 


LOCOMOTIVE  SPARKS. 


The  results  show  that  when  the  boiler  was  worked  under 
conditions  which  gave  an  evaporation  of  about  5  pounds  of 
water  per  square  foot  of  heating-surface  per  hour,  5.2  per  cent 
of  sample  E  was  lost  in  the  form  of  sparks  and  cinders;  also, 
that  5  per  cent  of  sample  D  was  lost  from  the  same  cause,  and 
so  on.  When  the  rate  of  evaporation  was  about  10,  the  losses 
by  sparks  amounted  to  22.1  per  cent  and  18.6  per  cent  cf 
samples  E  and  D,  respectively.  It  is  significant  that,  with  one 
exception,  those  samples  giving  the  highest  evaporation  also 
gave  the  largest  spark-losses.  Two  conditions  probably 
account  for  this  fact.  First,  the  purer  coals  have  a  lower 
specific  gravity  and,  hence,  respond  to  the  draft-action  more 
easily  than  coals  intermixed  with  non-combustible  matter ; 
secondly,  in  general,  the  lighter  the  ash,  the  larger  the  per- 
centage of  ash  which,  instead  of  falling  through  the  grate, 
passes  out  with  the  sparks  and  adds  its  mass  to  thfeir  weight. 

TABLE  III. 

SHOWING  CHEMICAL  ANALYSIS  OF  SPARKS  FROM  THE 
PURDUE  LOCOMOTIVE,  SCHENECTADY  NO.  1,  WHEN 
USING  BRAZIL  BLOCK  COAL. 


b| 

^  o 

Composition  of  Sparks.* 

it 

SS?.! 

tr.  ^ 

|Q 

umber. 

otal  Pounds  of  I 
Coal  Fired  per  I 

ounds  of  Dry  Cc 
per  Square  Foe 
Grate-surface  p 
Hour. 

S--I 

cAgE 

lit 

er  Cent  of 
Fixed  Carbon. 

o 

Iff 

er  Cent  of 
Combined 
Moisture. 

5  M 
u^ 
i'o 

ounds  of  Dry  C 
Equivalent  to  S 
losses  per  Hour. 

Qi;? 

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£ 

h 

Cu 

CH 

OH 

& 

Pu, 

cu 

2U 

> 

I. 

II. 

III. 

IV. 

V. 

VI. 

VII. 

VIII. 

IX. 

X. 

XI. 

i 

1,074 

61 

61.5 

61.74 

4.36 

1.82 

32.08 

46 

•75 

4  3 

2 

1,078 

84 

95-i 

64.88 

4.i6 

1.82 

29.14 

77 

.81 

7  2 

3 

i,  086 

124 

128.6 

71.32 

3.45 

1.66 

23.57 

in 

.86 

10.2 

4 

1,038 

241 

^76.3 

76.44 

3-29 

1.86 

18.41 

161 

•9I 

T5  5 

*  All  chemical  analyses  were  made  by  Charles  D.  Test,  A.C.,  under  the   direction  of  Dr. 
W.  E.  Stone. 


CINDERS  AND  SPARKS. 


33 


13.  Heating  Value  and  Coal  Equivalent  of  Sparks. An 

analysis   of  sample   sparks   obtained   under   different   rates   of 


•S»aVdS  JO  QNnOd  3NO  OJ. 
3mVA  ONI1V3H  Nl  lN31VAinS)3  "WOO  dO  SaNOOd 


combustion    when    using    Brazil    block    coal    is    presented    in 
Table  III. 

Among  the  significant  facts  disclosed  by  this  table  is  that 


34 


LOCOMOTIVE  SPARKS. 


relating  to  the  varying  fuel-value  of  the  sparks.  Thus  the 
sparks  which  result  from  a  rate  of  combustion  of  61  pounds  of 
coal  per  square  foot  of  grate  per  hour  are  composed  of  one-third 
ash,  while  those  which  were  obtained  under  a  rate  of  combus- 
tion of  241  pounds  have  less  than  one-fifth  their  bulk  composed 
of  ash;  in  other  words,  as  the  weight  of  sparks  increases,  their 
fuel-value  increases. 

From  the  facts  given  in  Table  III,  the  relationship  between 
the  rate  of  combustion  and  the  fuel-value  of  sparks  resulting 
may  be  established.  Such  a  relationship  is  shown  by  Fig.  8, 
which  shows  the  fraction  of  a  pound  of  coal  that  is  the 
equivalent  of  a  pound  of  sparks,  which  may  result  from  different 
rates  of  combustion.  By  use  of  this  curve  an  estimate  of  the 
value  of  the  spark-  and  cinder-losses  for  the  seven  tests  pre- 

TABLE  IV. 

SHOWING  HEATING  VALUE  OF  SPARKS  FROM  THE  PURDUE 
LOCOMOTIVE,  SCHENECTADY  NO.  1,  WHILE  USING  BRAZIL 
BLOCK  COAL. 


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6 

35 

3 

4.88 

2017.7 

115.29 

177-3 

.851 

150.9 

7-5 

7 

15 

9 

4.99 

2I2I.O 

121.20 

293-5 

.856 

251.2 

ii.  9 

CINDERS  AND  SPARKS.  35 

viously  under  consideration  may  be  had.  Such  an  estimate  in 
terms  of  equivalent  weight  of  coal  is  shown  in  Table  IV. 

The  values  given  in  Column  VIII  of  this  table  (Table  IV) 
were  taken  directly  from  the  curve  in  Fig.  8.  Those  in  Column 
IX  were  obtained  by  multiplying  the  values  in  Columns  VII 
and  VIII.  The  values  in  Column  X  were  obtained  by  dividing 
100  times  the  values  in  Column  IX  by  the  values  in  Column  V. 

It  will  be  seen  that  the  spark-  and  cinder-losses  measured 
in  terms  of  the  equivalent  weight  of  coal  are,  for  the  test  for 
which  the  power  was  lightest,  equivalent  to  22.7  pounds  per 
hour  and  for  the  test  for  which  the.  power  was  highest,  251.2 
pounds  per  hour;  these  values  being  equivalent  to  2.9  per  cent 
and  11.9  per  cent  of  the  weight  of  coal  fired  respectively. 

Too  much  emphasis  cannot  be  given  the  fact  that  these 
results  were  derived  while  the  engine  was  working  under  con- 
ditions that  are  in  no  wise  exceptional  and  the  fact  that  they 
show  that  more  than  1 3  per  cent  of  the  fuel  which  passes  the 
furnace-door  may  completely  pass  the  heating-surface  of  the 
boiler  unconsumed,  h  one  which  should  merit  attention. 

It  has  already  been  shown  that  the  size  of  the  sparks  varies 
with  the  extent  of  the  spark-losses.  It  should  now  be  evident 
that  under  low  rates  of  combustion,  the  solid  matter  discharged 
from  the  top  of  the  stack  consists  of  a  very  fine,  almost  sooty 
deposit,  having  a  very  low  fuel-value,  while  as  the  volume  of 
sparks  is  increased,  the  size  of  individual  particles  becomes 
greater  and  their  fuel-value  is  also  increased. 

14.  Conclusions  as  to  Cinder-  and  Spark-losses. — The 
results  of  the  investigations  herein  referred  to  and  in  part 
described,  justify  the  following  general  conclusions : 

1.  Sparks  are  composed  of  partially  consumed  coal  and 
ash. 

2.  The  total  weight  of  cinders  and  sparks  passing  the  heat- 


36  LOCOMOTIVE  SPARKS. 

ing-surface  of  the  boiler  of  a  locomotive  increases  as  the  rate 
of  combustion  is  increased,  and  under  conditions  approaching 
maximum  production  may,  in  connection  with  narrow  fire- 
boxes, equal  20  per  cent  of  the  weight  of  coal  fired. 

3.  Other  things  being  equal,  it  is   likely  that  the  condition 
of  the  fire  and  the  character  of  the  exhaust  have  considerable 
influence  upon  the  weight  of  cinders  produced. 

4.  The  fuel-value  of  a  unit  weight  of  sparks  or  of  cinders 
increases  as  the  volume  discharged  increases. 

5.  The  relation  between  the  weight  of  cinders  deposited  in 
a  long  front-end  and  the  weight  of  sparks  discharged  from  the 
top  of  the  stack   is   not   clearly  defined  by  the  experiments, 
since  in  general  it  must  be  a  function  of  the  length  of  the  test 
and  of  the  carrying  capacity  of  the  front-end,  but  under  high 
rates  of  combustion  it  appears  that  the  weight  discharged  from 
the  top  of  the  stack  is  in  excess  of  that  from  the  front-end. 

6.  The   size   of  sparks  varies  with   the   amount   produced. 
Thus,  when  conditions  are  such  as  result  in  small  spark-losses, 
the    sparks    themselves    are    insignificant    in    size,    while    the 
reverse  conditions  result  in  increased  size  of  sparks. 

7.  A   coal   burning  to  light  ash  gives  a  higher  spark-loss 
than  one  burning  to  clinker. 


CHAPTER   IV. 
SPARK-PREVENTION— FRONT-END    ARRANGEMENTS. 

15.  Spark-prevention. — The  problem  of  spark-prevention 
is  beset  with  difficulties.      To  secure  the  high  rates  of  combus- 
tion which  are  necessary  in  locomotive  service,  there  must  be 
a  free  passage  for  air  and  for  the  products  of  combustion  from 
the  grate  to  the  top  of  the  stack.      Anything  which  may  be 
interposed  in  the  currents  of  gases  moving  along  this  course 
affects  the  draft  and  generally  interferes  with  its  action.      To 
employ  obstructions  which  will  serve  in  suppressing  all  escape 
of  sparks  from  the  stack  would  choke  the  draft  and  make  the 
locomotive  inoperative.      In  the  practical  working  out  of  the 
whole  problem,    therefore,    spark-prevention   is   considered  as 
constituting  but  one  of  several  factors,  freedom  of  draft  and  its 
uniform  action  over  the  whole  area  of  the  grate  constituting 
other  and  equally  important  factors.      Thus  it  is  that  so-called 
spark-arresters  are  inseparably  connected  with  draft  appliances 
and  that  both  together  go  to  make  up  the  front-end   arrange- 
ment.     Again,  the  construction  of  the  furnace  may  affect  the 
volume  of  sparks  produced,  the  presence  of  a  brick  arch  usually 
operating  to  reduce  spark  production. 

16.  Increased    Grate-area. — Where   a   given    quantity  of 
fuel  is  to  be  burned,  the  effect  of  increasing  the  grate-area  is 
to    lower    the    rate   of  combustion   per  foot   of  grate-surface. 
This  means  that  the  volume  of  air  which,  in  passing  a  smaller 
grate,   would  flow  in   strong  currents,   will,   when  distributed 

37 


38  LOCOMOTIVE  SPARKS. 

over  the  area  of  a  larger  grate,  flow  much  less  rapidly. 
Hence,  it  may  be  said  that  increasing  the  grate-area  diminishes 
the  intensity  of  the  draft-action  upon  the  fire.  With  a  less 
energetic  draft-action,  the  production  of  sparks  is  necessarily 
reduced.  Obviously,  the  grate  cannot  be  regarded  as  a  spark- 
arrester,  but  since  the  grate  is  the  source  from  which  sparks 
arise,  and  since  when  other  things  remain  the  same,  an 
increase  in  its  area,  diminishes  the  volume  of  sparks  produced, 
its  proportions  are  not  to  be  omitted  in  a  consideration  of  the 
general  subject  of  spark-prevention. 

17.  The  Brick  Arch. — The  form  of  the  brick  arch  and  its 
location  within  the  fire-box  is  well  shown  by  Fig.  9  which  is 
a  vertical  section  of  the  furnace  end  of  a  locomotive  boiler. 
In  the  case   illustrated   the   arch  is  supported   upon  studs  or 
brackets  in  the  side-sheets  of  the  furnace  and  extends  from  the 
front-sheet  obliquely  backward.      By  its  presence  the  length 
of  flame-way  is  increased  and  particles  of  fuel  leaving  the  grate 
are  thereby  held  in  suspension  for  a  longer  time  before  entering 
the  tubes,  the  result  being  that  particles  which  would  otherwise 
be  sparks  or  cinders  are  in  many  cases  completely  burned  to 
ash.      The  arch,   also,  serves  to  distribute  the  draft  over  the 
grate  and  in  so  doing  it  doubtless  contributes  to  the  efficiency 
of  the  furnace-action. 

From  the  furnace  the  sparks  pass  directly  to  the  front-end, 
and  it  is  here  that  provision  for  receiving  them  is  chiefly  pro- 
vided. 

18.  A    Typical    Front-end    arrangement,     as     used     on 
Schenectady  No.    2,   the   experimental   locomotive  at  Purdue 
University,  is  shown  in  Fig.  10. 

The  exhaust-steam  from  the  cylinders  passes  through  the 
exhaust-ports  into  the  exhaust-pipe,  E.  From  E  it  passes 
through  the  exhaust-tip,  /,  and  is  directed  upwards  through 


SPARK-PREVENTION— FRONT-END  ARRANGEMENTS.  39 

the  petticoat-pipes,  P,  and  out  by  the  stack,  5.  This  action 
produces  a  partial  vacuum  in  the  smoke-box,  in  response  to. 
which  a  current  of  hot  gases  is  induced  in  the  tubes  T.  The 
hot  gases  finding  their  exit  from  the  tubes  are  at  once  inter* 


FIG.  9. 

cepted  by  the  diaphragm,  or  baffle-plate,  D,  by  which  they 
are  deflected  downwards,  as  shown  by  the  arrows.  The 
diaphragm  begins  above  the  top  row  of  tubes  and  extends 
obliquely  downwards  terminating  in  a  variable  slide,  V,  which 
may  be  raised  or  lowered  through  a  considerable  range  to  meet 
the  varying  conditions  of  service. 


4°  LOCOMOTIVE  SP4RKS. 

Beyond  the  diaphragm  is  the  netting,  N,  which  divides  the 
smoke-box  into  a  lower  and  an  upper  chamber.  The  door, 
(7,  is  interposed  in  the  netting  to  give  access  to  the  upper 


FIG.  10. 


chamber.  Above  the  netting  are,  or  may  be,  petticoat-pipes, 
/*,  though  in  many  locomotives  they  are  entirely  omitted. 
Above  the  petticoat-pipes  is  the  stack,  5.  At  //"is  a  cylindrical 
extension  (not  shown)  which  is  known  as  the  cinder-pocket, 


SPARK-PREVENTION— FRONT-END  ARRANGEMENTS.  41 

through  which  the  cinders  collecting  in  the  front-end  may  be 
removed.  The  course,  therefore,  of  the  gases  passing  under 
the  diaphragm  is  through  the  netting,  in  and  around  the  petti- 
coat-pipes, where  they  mingle  with  the  jet  of  exhaust-steam 
and  thence  out  through  the  stack.  It  will  be  seen  that  a  spark 
which  is  to  pass  out  at  the  top  of  the  stack  is  first  met  as  it 
emerges  from  the  tubes  by  the  diaphragm  against  which  it 
impinges.  From  the  diaphragm  it  is  deflected  downward,  and 
after  passing  the  narrow  opening  below  the  diaphragm  it  rises 
to  the  netting.  If  it  is  very  small  it  may  at  once  pass  the 
netting.  If  it  is  large  it  will  be  churned  about  in  the  front- 
end  and  hammered  against  the  netting  until  it  is  sufficiently 
pulverized  to  go  through.  It  is  by  this  process  that  particles 
which  otherwise  would  be  discharged  as  live  sparks  have  all 
the  fire  hammered  out  of  them  before  they  reach  the  top  of 
the  stack.  A  detailed  description  of  the  several  elements 
entering  into  the  construction  of  the  front-end  is  as  follows: 

19.  Diaphragm  or  Baffle-plate.  —  The  function  of  the 
diaphragm  is  twofold.  First,  it  acts  as  a  deflector  to  throw 
the  solid  particles  away  from  the  point  of  strongest  exhaust- 
action,  and  to  break  up  large  particles  which  impinge  against 
it.  Secondly,  it  acts  as  draft-regulating  device.  If  the  dia- 
phragm were  absent,  the  upper  rows  of  tubes,  owing  to  their 
proximity  to  the  exhaust-jet,  would  be  affected  by  the  exhaust- 
action  more  than  the  lower  tubes.  The  diaphragm  acts  as  a 
shield  to  the  upper  tubes,  checking  the  draft  action  in  them 
and,  by  so  doing,  augmenting  the  current  in  the  lower 
tubes.  If  the  draft  is  not  well  distributed  in  the  tubes, 
the  fuel  burns  unevenly  and  the  steaming-action  of  the 
boiler  is  impaired.  Mr.  C.  H.  Quereau*  gives  the  follow- 

*  Report  to  International  Railway  Congress,  Paris,  1900. 


LOCOMOTIVE  SPARKS. 


ing   as   present  American   practice  (1900)   in   the  design  and 
arrangement  of  the  diaphragm : 


FIG.  ii. 

"Fig.  ii  shows  the  types  of  diaphragms  generally  used. 
Arrangement  a,  with  the  plates  back  of  the  exhaust-pipe,  is 
standard  with  eighteen  roads ;  arrangement  /;,  with  the  plates 
extended  forward  of  the  exhaust-pipe,  is  standard  with  nine 


SPARK-PREYENTION— FRONT-END  ARRANGEMENTS.  43 

roads.  Arrangement  b  sweeps  the  cinders  from  the  front-end 
so  that  it  is  not  necessary  to  clean  them  either  on  the  road  or 
at  terminals,  and  the  cinder-hopper,  with  the  chances  of  its 
leaking,  are  done  away  with.  Two  roads  use  the  arrangement 
shown  in  c.  What  its  special  advantage  is  does  not  appear. 
Another  arrangement  of  two  plates  is  illustrated  by  d,  which 
is  used  by  two  roads  on  boilers  which  are  larger  than  62  inches 
in  diameter  at  the  forward  ring.  With  boilers  of  this  size  it  is 
frequently  difficult  to  distribute  the  draft  uniformly  over  the  fire 
and  at  the  same  time  properly  clean  the  cinders  from  the  front- 
end.  Design  d  does  this  admirably." 

' '  There  has  been  little  change  in  the  general  design  of  the 
diaphragm  since  1890.  Three  roads  have  moved  their  plates 
from  in  front  of  the  exhaust-pipe  to  back  of  it,  and  three  have 
reversed  this.  One  road  writes  as  follows :  '  The  only  change 
we  have  made  since  1 890  has  been  to  put  the  diaphragm  back 
of  the  exhaust-pipe  and  steam-pipes  to  overcome  the  excessive 
wear  of  these  pipes.  We  also  find  the  change  has  promoted 
combustion.' 

"It  is  the  almost  universal  custom  to  use  an  adjustable 
plate  on  the  fixed  plate  with  which  to  change  the  distance  from 
the  bottom  edge  of  the  diaphragm  to  the  bottom  of  the  front- 
end  and  in  this  way  distribute  the  draft  evenly  over  the  flues 
and  grate. " 

20.  Netting. — The  purpose  of  the  netting  is  to  prevent 
particles  of  fuel  from  passing  out  of  the  stack  in  a  state  of 
ignition.  It  must  be  sufficiently  open  to  permit  the  furnace- 
gases  to  pass  freely  through  and  to  minimize  the  danger  of  its 
filling  up  with  smoky  deposits.  It  must  be  sufficiently  close 
to  prevent  escape  from  the  stack  of  such  larger  particles  as  are 
likely  to  be  in  a  state  of  ignition. 


44 


LOCOMOTIVE  SPARKS. 


Thus,  Mr.  Quereau*  reports  as  follows: 
"  Present  practice,  in  so  far  as  the  general  arrangement  of 
the  netting  is  concerned,  is  shown  in  Fig.  12,  from  which  it 


FIG.  12. 

appears  that  four  roads  use  arrangement  a  and  twenty-three 
roads  b.  The  controlling  reason  for  the  design  b  seems  to  be 
convenience  in  getting  at  the  exhaust-tip  and  baffle-plates,  and 

*  International  Railway  Congress,  Paris,  1900. 


SPARK-PREVENTION-FRONT-END  ARRANGEMENTS.  45 

an  increased  area  of  netting.  Diagram  c,  commonly  called 
the  basket-netting,  is  used  to  some  extent.  This  is  the  most 
convenient  form,  in  so  far  as  ease  in  getting  at  the  deflector- 
plates  and  steam-pipe  joints  is  concerned,  and  equally  as  con- 
venient as  form  b  when  it  is  necessary  to  reach  the  tip,  but,  in 
front-ends  of  large  diameters,  form  c  is  liable  to  cause  an 
accumulation  of  cinders  in  the  front-end,  probably  because  the 
currents  around  each  side  meet  in  front,  causing  an  eddy,  and 
because  the  currents  do  not  strike  the  netting  at  right  angles, 
increasing  the  resistance." 

' '  The  preference  of  the  roads  as  to  the  material  used  in  the 
netting  is  shown  by  the  fact  that  twenty  use  woven  wire  and 
seven,  perforated  plates.  The  favorite  dimensions  for  wire- 
netting  is  that  with  2-J-  X  2j  meshes  per  square  inch,  with  the 
wires,  .12  inch  in  diameter,  used  by  nine  roads.  Next  comes 
a  netting  with  the  same  mesh,  but  the  wire  .109  inch  in 
diameter,  used  by  five  roads.  Netting  with  meshes  as  fine  as 
8x8  per  square  inch  and  wire  .049  inch  in  diameter  is  used 
by  one  road  which  runs  through  a  country  specially  liable  to 
fires. " 

"In  the  perforated  plates  the  openings  are  usually  about 
i£  X  T3^  mch  or  i  *nck  w^  the  corners  filletted,  with  a  J-inch 
bridge  between,  the  sheet  through  which  the  holes  are  punched 
being  usually  \  inch  thick,  as  shown  in  Fig.  13." 

21.  Petticoat-pipe  can  only  be  used  with  advantage  when 
the  exhaust-nozzle  is  set  low.  In  such  cases  it  helps  to  dis- 
tribute the  action  of  the  exhaust,  generally  permitting  the 
deflector-plate  to  come  higher  than  otherwise.  The  result  is 
a  more  open,  or  less  obstructed  front-end.  The  petticoat-pipe 
provides  additional  channels  through  which  the  gases  of  the 
smoke-box  are  fed  to  the  jet  of  steam  and  by  so  doing  they 
serve  to  transform  the  comparatively  small  and  powerful  jet  of 


46 


LOCOMOTIVE  SPARKS. 


steam  into  a  larger  but  less  intense  stream  of  mixed  gase.s  and 
steam.  This  issuing  from  the  first  petticoat-pipe  becomes  the 
moving  force  to  act  upon  other  portions  of  gas;  the  moving 
stream  augmented  in  size  by  fresh  additions  enters  the  second 


.ruuuLnJLnJLrJ 

FIG.  13. 

petticoat-pipe  from  which  it  issues  to  again  repeat  the  process 
before  entering  the  base  of  the  stack.  The  petticoat-pipes 
serve  to  distribute  the  load  of  smoke-box  gases  taken  up  by 
the  steam-jet,  and  by  defining  the  boundaries  of  the  combined 
jet,  they  prevent  its  losing  energy  by  breaking  up  into  eddies. 
In  so  far  as  they  accomplish  this  they  contribute  to  the  effi- 
ciency of  the  exhaust-action. 

As  a  practical  matter  it  should  be  said  that  experience 
proves  that  the  adjustment  of  the  petticoat-pipes  to  a  proper 
height  relative  to  the  other  elements  affecting  the  draft  is  a 
very  important  matter.  A  few  inches  higher  or  lower  may 
have  a  decided  effect  on  the  steaming  qualities  of  the  boiler. 
In  many  cases  petticoat-pipes  are  entirely  omitted  and  when 
used  they  may  be  double  as  shown  by  Fig.  10,  or  single. 

22.  Exhaust-pipe. — There  are  two  forms  of  exhaust-pipes 
in  general  use,  the  single  and  the  double.  In  the  single 
exhaust-pipe  the  steam  from  both  cylinders  escapes  through 
the  same  tip  as  shown  by  Fig.  14.  The  double  exhaust-pipe 


SPARK-PREVENTION— FRONT-END  ARRANGEMENTS. 


47 


allows  the  steam  from  each  cylinder  to  exhaust  through  an 
independent  tip  as  shown  by  Fig.   15. 

The  object  of  any  design  or  arrangement  of  exhaust-pipe  is 
to  serve  in  carrying  off  the  exhaust-steam  from  the  cylinders 


FIG.  14. 

with  the  least  amount  of  back  pressure  and  at  the  same  time 
give  a  jet  having  sufficient  energy  to  produce  the  required 
draft.  A  double  nozzle  provides  a  separate  exit  for  the  steam 
from  each  cylinder ;  a  single  nozzle  requires  the  steam  from 
both  cylinders  to  emerge  from  the  same  opening.  With  the 
sinele  nozzle,  however,  the  passages  are  kept  separated  until 


OF  THE 
UNIVERSITY 


48 


LOCOMOTIVE  SPARKS. 


the  point  of  discharge  is  nearly  reached.  When  the  exhaust- 
pipe  is  very  short  or  when  other  details  of  the  whole  arrange- 
ment of  ports  and  pipes  are  such  that,  a  single  nozzle  might 
allow  steam  exhausted  from  one  cylinder  to  pass  into  the 


FIG.  15. 

exhaust-passage  of  the  other  cylinder,  a  double  exhaust-pipe 
must  be  used.  Under  conditions  such  as  are  shown  by  Figs. 
14  and  15,  it  is  perhaps  sufficient  to  say  that  good  practice 
involves  both  forms  and  that  both  forms  have  their  advocates. 
The  Master  Mechanics'  Committee,  however,  recommends  the 


SPARK-PREVEN TION—FRCN T-END  ARRANGEMEN  TS. 


49 


single  pipe  (Fig.  14)  as  the  more  efficient  of  the  two  arrange- 
ments. 

23,  Exhaust- tip. — The  exhaust- tip  is  the  fixture  at  the 
end  of  the  exhaust-pipe.  It  is  the  tip  which  governs  the  size, 
shape,  and  velocity  of  the  exhaust-jet.  Exhaust-tips  may,  in 
general,  be  either  fixed  or  variable.  Fixed  tips  are  designed 
to  meet  the  average  conditions  of  service  and  are  of  various 
forms  as  shown  by  Fig.  1 6. 


i 


FIG.  16. 

The  variable  exhaust-tips  are  so  designed  that  the  area  of 
the  opening  may  be  changed  at  the  will  of  the  engineer  as  the 
conditions  of  service  may  require,  or  controlled  by  the  position 
of  the  reverse  lever  or  through  the  action  of  some  other  part  of 
the  mechanism  of  the  engine.  In  theory  the  variable  exhaust- 
tip  is  correct,  but  the  difficulties  to  be  overcome  in  its  design 
and  operation  have  thus  far  prevented  it  from  coming  into 


50  LOCOMOTIVE  SPARKS. 

general  use  in  this  country.  For  a  discussion  of  the  relative 
merits  of  fixed  and  variable  exhaust-tips  as  used  on  foreign  loco- 
motives, the  reader  is  referred  to  a  report  by  Mr.  Eduoard 
Sauvage  to  the  International  Railway  Congress,  Paris,  1900.* 

24.  Smoke-stack. — The  smoke-stack  serves  to  convey  the 
gases  and  the  exhaust-steam  from  the  smoke-box  to  the  outer 
air.      There  are  two  general  classes,  the  open  stack  and  the 
diamond    stack.      Open   stacks   may   be   straight   or   tapered. 
Until   quite    recently    they  have    ordinarily  been    straight    as 
shown   by   Fig.   33,  but  they  are   now   generally   tapered   as 
shown  by  Fig.   10  and  by  Figs.    23   to  29.      The  opinion   is 
prevalent   that  the   double-tapered   stack    (Fig.    10)    is    more 
efficient  than  the  straight  stack  and  it  is  known  to  be  less  sub- 
ject to  wear  from  the  action  of  sparks. 

The  open  stack  is  used  in  connection  with  the  extension 
front;  the  diamond-stack,  in  connection  with  the  short  front- 
end.  Fig.  10  is  a  type  of  the  former,  and  Fig.  17  of  the  latter. 
The  diamond-stack  is  essentially  a  combination  of  stack  and 
spark-arrester.  The  solid  particles  of  fuel  impinge  against  the 
cone  at  the  top  of  the  stack  and  are  deflected  into  the  bonnet, 
If  small,  they  may  be  swept  out  through  the  netting  at  the 
top,  but  if  large  they  are  retained  in  the  bonnet  where,  by  the 
repeated  action  of  the  exhaust,  they  are  hammered  about  until 
broken  sufficiently  to  pass  through  the  netting. 

The  diamond-stack  is  the  older  type  of  construction,  and 
while  still  somewhat  used  it  is  nevertheless  gradually  disap- 
pearing from  service. 

25.  Extended  Front-end. — The  extended    front-end    is  a 
necessary  part  of  the  general  arrangement,  the  details  of  which 
constitute  the  subject  of  the  several  paragraphs  immediately 

*  Railroad  Gazette,  pp.  448-450,  June  29,  1900. 


SPARK-PREYENTION-FRONT-END  ARRANGEMENTS.  $1 


FIG.   17. 


52  LOCOMOTIVE  SPARKS. 

preceding,  but  its  dimensions  may  be  varied  within  rather  wide 
limits.  Originally  it  was  intended  to  be  large  in  order  that  it 
might  supply  sufficient  space  in  which  cinders  could  be 
entrapped.  This  is  shown  by  the  following  statement  of  the 
inventor,  as  quoted  by  Mr.  Bell :  * 

' '  The  nature  of  my  invention  consists  in  extending  the 
smoke-arch  or  smoke-box  (front-end)  so  far  beyond  the 
chimney  (stack)  and  the  blast-pipe  that  the  sparks  and  cinders 
ejected  from  the  stack  of  pipes  (tubes)  connecting  the  smoke- 
arch  (front-end)  with  the  furnace  may  be  thrown  so  far  forward 
beyond  the  draft  or  current  of  smoke  passing  from  the  stack 
(the  tubes)  to  the  chimney  (stack)  as  to  fall  down  and  settle  or 
be  retained  within  the  smoke-box.  ...  I  have  found  that  by 
extending  the  smoke-box  (front-end)  some  considerable  dis- 
tance, that  is,  about  1 8  inches  or  more,  in  manner  as  described 
and  represented,  beyond  the  course  of  the  draft,  most,  if  not 
all  of  the  sparks  and  cinders,  will  pass  beyond  the  current  of 
smoke  and  be  deposited  in  the  smoke-box  (front-end)." 

In  practice  it  is  found  that  while  the  front-end  will  retain 
some  sparks,  it  cannot  hold  all  which  would  naturally  accumu- 
late except  for  a  brief  interval.  This  being  true  the  difficulties 
of  freeing  the  front-end  of  its  accumulation,  between  terminals, 
has  led  to  the  general  adoption  of  such  proportions  as  will  give 
best  results  in  the  matter  of  draft,  regardless  of  its  capacity  for 
cinders.  Data  already  quoted  (Table  III,  Chapter  III)  show 
that  with  a  front-end  so  designed  as  to  be  capable  of  holding 
large  amounts  of  sparks,  the  volume  passing  out  of  the  stack 
is  greater  than  that  which  is  entrapped.  In  general,  therefore, 
it  may  be  said  that  the  front-end  of  to-day  serves  the  purpose 
of  providing  room  for  a  liberal  area  of  netting.  It  is  not 
regarded  as  of  value  as  a  means  for  retaining  cinders. 


*  J.  Snowden  Bell  before  the  Western  Railway  Club,  September,  1899. 


SPARK-PREVENTION— FRONT-END  ARRANGEMENTS.  53 

26.  Practice  in  Front-end  Arrangements. — Thus  far  we 
have  considered  the  various  details  which  have  to  do  with  the 
maintenance  of  draft  and  the  prevention  of  sparks.  We  may 
now  take  a  more  general  survey  to  ascertain  what  are  the 
differences  which  characterize  present-day  practice,  and  in  so 
doing  will  again  have  resort  to  the  excellent  paper  of  Mr.  Bell 
from  which  the  following  is  largely  abstracted  and  arranged. 

Referring  first  to  the  diamond  stack,  attention  is  called 
to  Fig.  17,  which  represents  the  standard  of  the  Union  Pacific 
Railway  for  the  past  fifty  years,  and  to  Figs.  18  and  19,  which 
show  the  adaptation  of  this  practice  to  some  large  consolida- 
tion engines  recently  built  for  the  same  road.  It  will  be  seen 
that  the  smoke-box  is  unobstructed  by  either  diaphragm  or 
netting,  that  the  nozzles  are  low  and  that  they  have  a  long 
petticoat-pipe  above  them.  The  spark-arresting  is  accom- 
plished in  the  stack  which  is  enormously  enlarged  to  accomo- 
date  a  sufficient  area  of  netting  and  which  carries  an  inverted 
"  cone  "  to  baffle  the  sparks.  Figs.  20  and  21  represent  the 
standard  stack  and  front-end  for  burning  wood,  of  the  Mexican 
Central  Railroad,  which  differs  from  those  already  described 
only  in  minor  details  and  in  the  proportion  of  parts. 

Returning  now  to  the  open  stack  and  the  extended  front 
so  common  in  present-day  practice,  attention  should  first  be 
given  the  particular  arrangement  recommended  by  the  Master 
Mechanics'  Committee  on  Exhaust-pipes  and  Steam-passages, 
of  1896.  The  Committee  made  elaborate  experiments  and 
established  dimensions  for  exhaust-pipe,  tip,  petticoat-pipes, 
and  stack  which-  are  believed  to  give  maximum  efficiency. 
These  are  shown  by  Fig.  22. 

While  the  committee  recommended  that  the  smoke-box  be 
made  sufficiently  long  to  permit  a  cinder-pocket  or  cinder-pot 
for  the  discharge  of  cinders,  to  be  located  in  front  of  the  cylin- 


54 


LOCOMOTIVE  SPARKS. 


77! 


3'll"X » 


SPARK-PRE MENTION -FRONT-END  ARRANGEMENTS.  55 


FIG.   19. 


56  LOCOMOTIVE  SPARKS, 

der-saddle,  as  shown  in  Fig.  25,  the  fact  was  generally  recog- 
nized that  the  smoke-box,  whether  long  or  short,  could  not, 
and  did  not  in  practice,  perform  to  any  extent  the  function  of 
a  cinder  receptacle  or  retainer. 


FIG.  20.  FIG.  21. 

In  further  discussion  of  the  general  subject,  the  Convention 
agreed  that  it  is  possible  to  so  arrange  the  front-ends  of 
locomotives  that  they  will  clear  themselves  of  cinders  without 
throwing  live  sparks.  (Topic  No.  2,  pp.  103-108,  Proceed- 
ings of  1898.) 


SPARK-PRE^ENTION-FRONT-END  ARRANGEMENTS. 


T 


FIG.  22. 


58  LOCOMOTIVE  SPARKS. 

The  length  of  the  front-end  was  not  definitely  fixed  by  the 
committee,  though  the  opinion  was  expressed  that  a  more 
efficient  arrangement  would  result  if  it  were  made  shorter  than 
was  then  (1896)  common  practice.  As  a  result  of  this  recom- 
mendation and  of  the  experience  of  master  mechanics  acting 
individually,  we  now  find  many  so-called  "  short  "  front-ends, 
though  many  of  the  long  or  "  extended  "  type  still  remain. 

The  general  design  of  the  Master  Mechanics'  Committee, 
as  applied  to  an  extended  front-end  is  shown  by  Fig.  23. 
The  extension  of  the  deflecting-plate  in  front  of  the  exhaust- 
pipe  is  for  the  purpose  of  clearing  the  front-end  of  cinders. 
Where  this  arrangement  is  employed,  the  cinder-pot  is  dis- 
pensed with.  Fig.  24  shows  a  self-cleaning  front  as  used  on 
Class  U  engines  of  the  Norfolk  &  Western  Railway.  Mr. 
W.  H.  Lewis,  Superintendent  of  Motive  Power  of  that  road,  in 
writing  to  Mr.  Bell,  with  reference  to  his  design,  well  states 
the  considerations  which  have  led  to  the  adoption  of  self-clean- 
ing front-ends.  He  writes  as  follows: 

' '  The  self-cleaning  features  of  these  are  practically  the 
same,  and  we  have  found  that  it  is  possible  to  do  away  entirely 
with  the  cinder-hopper  and  blower,  and  experience  no  trouble 
with  the  front  filling  with  cinders." 

"  I  beg  to  remind  you,  however,  that  the  general  rules  to 
be  observed  in  the  arrangement  of  these  spark-arresting  devices 
are  largely  dependent  upon  the  character  of  the  coal  and  the 
service  performed  by  locomotives,  and  the  position  of  the 
deflector  and  diaphragm-plates  can  only  be  determined  by  a 
careful  service  test.  The  satisfactory  results  which  we  are 
now  obtaining  have  thoroughly  convinced  us  that  it  is  not 
necessary  to  maintain  a  long-extended  front  as  a  receptacle 
for  cinders,  and  that  only  sufficient  extension  is  required  to 
insure  the  proper  area  of  opening  in  the  perforated  plates  or 


SPARK-PREVENTION— FRONT-END  ARRANGEMENTS.  59 


FIG.  23. 


6o 


LOCOMOTIVE  SPARKS. 


FIG.  24. 


SPARK-PREVENTION— FRONT-END  ARRANGEMENTS.  61 

netting  used  to  insure  a  free  draft;  in  fact,  in  the  number 
of  observations  which  we  made  prior  to  the  adoption  of  the 
device,  it  was  found  that  our  long-extended  fronts  accumulated 
the  maximum  amount  of  cinders  in  a  distance  of  ten  miles, 
in  heavy  mountain  service,  so  that  all  of  the  cinders  and 
sparks  which  entered  the  front-end  after  that  time  were 
necessarily  thrown  out.  We,  therefore,  felt  that  little  ad- 
vantage might  be  expected  from  simply  storing  the  cinders 
that  would  accumulate  in  going  a  distance  of  ten  miles  and 
running  a  further  distance  of  fifty  or  sixty  miles  without  any 
further  accumulation,  and  that  it  was  thoroughly  logical  to 
adopt  a  device  which  would  relieve  the  front  of  cinders 
entirely." 

A  front-end  which  in  its  length  very  nearly  conforms  to 
the  recommendation  of  the  Master  Mechanics'  Committee  is 
shown  by  Fig.  25.  This  is  from  the  drawings  of  certain  classes 
of  small  engines  on  the  C.  B.  &  Q.  Railway.  The  general 
arrangement  disclosed  by  the  figure  may  be  accepted  as 
common  to  very  many  locomotives  in  the  United  States.  An 
arrangement  not  uncommon  is  shown  by  Fig.  26,  the  illustra- 
tion being  taken  from  a  heavy  Atlantic  type  engine  of  the 
C.  B.  &  Q.  In  this  case  the  exhaust-nozzle  is  low  and  the 
general  plane  of  the  netting  high,  the  distance  between  being 
spanned  by  a  '  <  basket  ' '  form  of  netting.  The  diaphragm  is 
almost  entirely  absent  in  this  design,  the  whole  front  being 
quite  free  of  obstruction.  Another  arrangement,  somewhat 
similar  in  principle  but  involving  a  lower  deflector-plate  and 
petticoat-pipes  is  shown  by  Fig.  27. 

A  front-end  employed  on  ten  large  engines  of  the  Mexican 
Central  is  shown  by  Figs.  28  and  29.  It  will  be  seen  that  it 
is  very  short,  that  an  extension  of  the  deflector  is  brought  to 
a  point  forward  of  the  nozzle,  and  that  the  netting  does  not 


62 


LOCOMOTIVE  SPARKS. 


FIG.  25. 


SPARK-PREVENTION -FRONT-END  ARRANGEMENTS.  63 


FIG.  26. 


LOCOMOTIVE  SPARKS. 


FIG.  27. 


SPARK-PRE1SENTION-FRONT-END  ARRANGEMENTS.  65 

connect  with  the  deflector,  there  being  an  unobstructed 
space  of  17  inches  between  them.  Mr.  Johnstone  of  the 
Mexican  Central  in  writing  to  Mr.  Bell  of  this  front-end 
says: 

"You  will  see  that  we  are  using  the  master  mechanics* 
standard  nozzle  and  petticoat  arrangement,  with  what  we  call 
the  Mexican  Central  standard  deflecting-plate  and  netting 
arrangement.  This  gives  a  clear  opening  between  the  bottom 
of  the  netting  and  the  top  of  the  deflecting-plate  of  17 
inches."  To  this  Mr.  Bell  adds  that  "present  practice 
in  front-ends  is  plainly  marked  in  the  abandonment  of  the 
long-extended  smoke-box  by  the  Pennsylvania  railroad 
in  its  latest  and  most  approved  designs  of  locomotives, 
for  both  fast  passenger  and  heavy  freight  service.  Figs. 
30  and  3 1  show  the  front-end  arrangement  of  the  large 
H  5  and  H  6  consolidation  engines,  recently  built  by  that 
company,  and  the  same  design,  in  all  substantial  particulars, 
is  used  on  their  latest  construction  of  high-speed  passenger 
engines. " 

4 '  In  view  of  the  fact  that  this  front  is  doubtless  practically 
self-cleaning,  and  of  the  comparatively  large  diameter  of  the 
smoke-box,  it  may  be  suggested  that  it  could,  with  advantage 
and  without  sacrificing  any  netting  area,  be  further  shortened, 
as,  say,  10  inches  or  thereabouts.  Again,  if  a  cinder-pocket 
is  believed  to  be  desirable  with  this  or  any  other  design  of 
front,  it  would  seem  that  if  its  smoke-box  opening  were  made 
oblong,  with  the  greater  dimension  transverse  to  the  engine, 
the  free  discharge  of  the  cinders  would  be  facilitated  and  the 
length  of  front  necessary  to  accommodate  it  be  diminished. 
Among  other  meritorious  features  of  this  design,  attention  may 
be  called  to  the  disposition  of  the  netting,  whereby  as  great  an 
area  as  is  practicable  within  a  determined  length  of  front  is 


66 


LOCOMOTIVE  SPARKS. 


FIG.  28. 


SPARK-PREVENTION—  FRONT-END  ARRANGEMENTS.  67 


WIRE  NETTING 
NO.  3  MESH  NO.  11  WIRE 


FIG.  29. 


68 


LOCOMOTIVE  SPARKS. 


obtained,  and  the  sheets  are  inclined  relatively  to  the  trav- 
erse of  the  escaping"  products  of  combustion.  The  inward 
extension  of  the  stack,  while  by  no  means  a  novel  feature. 


FIG.  30. 

having  been  applied  in  English  engines  as  early  as  1860,  is 
also  believed  by  the  writer  to  be  of  substantial  practical  value. 
There  can  be  no  doubt  of  the  efficiency  of  this  front,  both  as 


SPARK-PREVENTION— FRONT-END  ARRANGEMENTS. 


69 


to  free  steaming  and  prevention  of  fire  throwing,  arid  it  has 
been  not  an  unimportant  factor  in  the  phenomenal  performance 
of  the  E  I  passenger  engines  on  the  Camden  &  Atlantic  Rail- 
road." 


FIG.  31. 

The  Coburn  front-end,  which  is  shown  in  Figs.  32,  33,  and 
34,  was  designed  by  the  late  Mr.  W.  P.  Coburn,  of  the  Chicago, 
Indianapolis  &  Louisville  Railway.  It  is  designed  to  break  up 
the  sparks  into  fragments  so  small  as  to  be  incapable  of  doing 
damage,  before  they  reach  the  stack.  This  is  accomplished  by 
a  suitable  arrangement  of  deflecting  plate  in  connection  with 
nests  of  long,  closely  set  cast-iron  spikes  extending  from  the 
front  door  and  head,  rearward  into  the  smoke-box.  The  cur- 
rent passing  from  the  deflector-plate  is  sent  upward  into  and 


7o 


LOCOMOTIVE  SPARKS. 


SPARK-PREVENTION— FRONT-END  ARRANGEMENTS. 


FIG.  35. 


72  LOCOMOTIVE  SPARKS. 

through  the  nests  of  spikes  already  referred  to.  In  making 
the  passage,  the  cinders  are  made  to  impinge  against  the  spikes 
which  are  set  in  their  way,  and  are  thereby  pulverized  to  the 
desired  degree  of  fineness.  Obviously,  this  front-end  is  self- 
cleaning. 

"The  Bell  front-end  as  in  service  in  21  X  26-inch  con- 
solidation engines  on  the  Baltimore  &  Ohio  Railroad  is  shown 
in  Fig.  35.  In  later  applications,  on  this  road  and  on  the 
Pittsburgh,  Bessemer  &  Lake  Erie  Railroad,  an  addition  has 
been  made  to  the  lower  end  of  the  deflecting-plate,  extending, 
on  a  slight  incline  to  a  line  in  front  of  the  exhaust-pipe,  on  the 
same  principle  as  that  of  the  self-cleaning  fronts  before  referred 
to.  The  deflecting-plate  is  punched,  with  lips  projecting 
toward  the  front  from  the  holes,  and  a  sheet  of  netting  is  placed 
in  front  of  it  to  intercept  any  cinders  that  may  pass  through 
the  holes.  The  main  portion  of  the  netting  is  set  in  three 
planes  or  in  '  *  saw-tooth  ' '  form  in  front  of  the  exhaust-pipe,  so 
as  to  present  approximately  vertical  surfaces  to  the  cinders  as 
they  pass  up  from  below  the  deflecting-plate,  and  a  i-inch 
clear  opening,  protected  by  a  lower  sheet  of  netting,  is  left 
between  the  two  front  inclined  sheets  to  prevent  clogging  by 
accumulation  of  cinders  between  them." 

27.  Authorities  on  the  Front-end. — Those  who  may  wish 
to  make  a  more  extended  study  of  front-end  arrangements  will 
find  an  abundance  of  material.  If  interested  in  the  proportions 
which  give  maximum  efficiency  to  details  of  usual  form,  they 
should  become  familiar  with  the  results  of  the  very  elaborate 
series  of  experiments  which  will  be  found  of  record  in  the 
Report  on  Exhaust-pipes  and  Steam-passages,  Proceedings  of 
the  Master  Mechanics'  Association,  1896.  These  experiments 
were  broadly  planned  and  faithfully  executed  under  the  direc- 
tion of  Mr.  Robert  Quayle,  Chairman  of  the  Committee, 


SPARK-PREVENTION— FRONT-END  ARRANGEMENTS.  73 

assisted  by  Mr.  E.  M.  Herr.  The  work  was  made  to  involve 
a  full-sized  locomotive  so  arranged  that  the  desired  data  could 
be  obtained  with  a  degree  of  accuracy  which  inspires  confi- 
dence in  the  general  conclusion  formulated  by  the  committee. 
Another  elaborate  series  of  experiments  designed  to  serve  the 
same  end,  but  involving  quite  a  different  plan  of  procedure,  was 
conducted  under  the  direction  of  Herr  von  Borries  and 
Inspector  Troske  of  the  Prussian  State  Railway.  An  account 
of  these  experiments,  translated  from  the  German,  was  pub- 
lished in  this  country  as  a  series  of  articles  by  the  American 
Engineer.  These  appeared  in  ten  of  the  twelve  issues  for  the 
year  1896. 

In  his  report  on  Draft  Appliances  to  the  International 
Railway  Congress,  Paris,  1900,  Mr.  C.  H.  Quereau  reviews 
both  the  work  of  the  Master  Mechanics'  Committee  and  the  von 
Borries-Troske  experiments  and  gives  in  condensed  form  the 
conclusions  which  they  justify. 

Those  who  are  more  interested  in  different  combinations  of 
the  details  should  read  a  paper  entitled  "  Draft  Appliances  of 
the  Locomotives  Exhibited  at  the  Columbian  Exposition, 
Chicago,"  which  was  read  by  Mr.  E.  M.  Herr  before  the 
November,  1893,  meeting  of  the  Western  Railway  Club  ;  also 
a  paper,  "  Locomotive  Front-ends,"  by  J.  Snowden  Bell,  given 
before  the  Western  Railway  Club  ;  and  in  this  connection, 
also,  Mr.  Quereau's  report  to  the  International  Railway  Con- 
gress to  which  reference  has  already  been  made. 


CHAPTER    V. 

ACTION   OF   THE    EXHAUST-JET   AND    DISTRIBUTION    OF 
SPARKS   WITHIN   THE    FRONT-END. 

28.  Experiments  to  Determine  the  Character  of  the 
Exhaust-jet. — The  action  of  the  exhaust-jet,  and  the  design 
and  arrangement  of  the  draft  appliances,  have,  as  previously 
noted,  been  carefully  investigated  by  a  committee  of  the 
American  Railway  Master  Mechanics'  Association.*  That 
part  of  the  work  which  related  to  the  action  of  the  exhaust-jet 
was  carried  on  at  the  locomotive  laboratory  of  Purdue  Uni- 
versity by  methods  which  may  be  described  as  follows : 

In  line  with  the  centre  of  the  stack  and  exhaust-pipe,  cast- 
iron  sleeves  were  fastened  to  the  outside  of  the  smoke-box 
(Fig.  36).  Through  these  were  fitted  pipes  I,  2,  3,  4,  and  5, 
arranged  to  slide  in  and  out  across  the  smoke-box,  and  having 
their  inner  ends  turned  down  to  a  fine  tip  with  sharp  edges 
bounding  the  orifices.  The  body  of  each  pipe  was  graduated 
to  tenths  of  inches,  the  scale  reading  from  a  reference-mark 
fixed  to  the  sleeve  on  the  outside  of  the  smoke-box.  If  the 
zero  of  the  scale  were  Drought  under  the  reference-mark,  the 
inner  edge  of  the  pipe  would  be  directly  under  the  centre  of 
the  stack,  and  directly  over  the  centre  of  the  exhaust-pipe. 
It  is  obvious  that  if  the  tip  of  any  pipe  be  surrounded  by  the 


*  Report    on    Exhaust-pipes    and    Steam-passages,    Master    Mechanics'' 
Proceedings,  1896.  pp.  58-143. 

74 


ACTION  OF  THE  EXHAUST-JET.  75 

jet  of  exhaust-steam,  the  velocity  of  the  latter  will  tend  to 
carry  steam  through  the  pipe  and  to  discharge  it  into  the 
atmosphere  outside  of  the  smoke-box.  It  can  be  shown  also 
that  the  force  which  the  steam  would  exert  in  its  effort  to  pass 
the  pipe  is  a  function  of  its  velocity;  hence  by  observing  the 
force  or  pressure  the  velocity  may  be  calculated.  Pressures 
were  observed  by  having  the  outer  ends  of  each  sliding  pipe 
connected  by  rubber  tubing  with  one  leg  of  a  manometer  or 
U-shaped  glass  tube  which  was  fastened  to  the  wall  of  the 
laboratory.  These  U  tubes  were  partially  filled  with  mercury, 
the  displacement  of  which  gave  the  pressure  transmitted 
through  the  tube.  If,  for  example,  the  tip  of  any  particular 
pipe  were  in  the  jet  of  steam,  its  manometer  would  show  pres- 
sure ;  if  it  were  withdrawn  from  the  jet,  its  manometer  would 
indicate  a  vacuum. 

Besides  these  sliding  pipes  in  the  smoke-box,  the  stack 
was  fitted  with  three  pipes  which  had  plain  ends  projecting 
beyond  the  inner  wall  about  a  quarter  of  an  inch.  These  side 
orifices  were  each  connected  with  a  manometer.  They  served 
to  show  the  extent  of  pressure  or  vacuum  existing  within  the 
stack  at  points  where  they  were  attached.  Their  exact  loca- 
tion is  shown  by  the  dimensions  in  Fig.  36. 

The  draft  was  measured  by  two  different  manometers,  and 
was  permanently  registered  by  a  Bristol  recording-gage. 
Indicators  were  used  to  show  the  steam  distribution  in  the 
cylinders,  and  a  special  indicator  fitted  with  a  light  spring  gave 
a  fine  record  of  the  back-pressure  line.  This  pressure  was  also 
recorded  by  a  Bristol  gage.  A  Boyer  speed-recorder  served 
as  a  means  for  maintaining  constant  speed  conditions. 

Observations  were  made  as  follows :  Desired  conditions  of 
speed  and  steam-pressure  having  been  obtained,  the  adjustable 
pipes  (i,  2,  3,  4,  and  5),  Fig.  36,  were  withdrawn  from  the 


76  LOCOMOTIVE  SPARKS. 

smoke-box  sufficiently  to  bring  them  entirely  clear  of  the 
exhaust-jet,  usually  to  a  distance  of  4!  inches  from  centre  of 
jet.  Then,  upon  signal,  all  manometer-gages  were  read  and 
all  other  observations  taken,  the  readings  being  taken  simul- 
taneously. Each  sliding  pipe  was  then  moved  inward  a  tenth 
of  an  inch  and  readings  repeated,  after  which  they  were  moved 
another  tenth,  and  so  on  until  the  tips  of  all  the  pipes  reach  the 
centre  of  the  exhaust-jet.  The  readings  thus  obtained  from 
the  pipes  1,2,  3,  4,  and  5,  Fig.  36,  were  entered  upon  a 
half-sized  drawing  representing  a  portion  of  the  cross-section 
of  the  smoke-box,  the  position  of  each  entry  showing  the  exact 
location  to  which  the  numerical  readings  applied.  Upon  the 
diagram  of  pressures  thus  obtained  lines  were  drawn  through 
points  showing  neither  vacuum  nor  pressure.  These  lines 
were  assumed  to  represent  the  border  of  the  steam-jet,  and  are 
the  outside  lines  in  Figs.  37  to  39.  In  a  similar  manner,  lines 
were  drawn  inside  of  those  just  described,  each  line  connecting 
points  representing  the  same  pressure.  These  also  appear  in 
Figs.  37  to  39,  but  the  numbers  given  in  connection  therewith 
do  not  represent  pressure,  but  velocity  in  feet  per  second,  as 
calculated  from  the  indications  of  the  gages.  Each  line,  there- 
fore, represents  a  chain  of  particles  which  have  the  same 
velocity,  the  value  of  which,  in  feet  per  second,  is  shown  by 
the  figure  attached  thereto. 

The  three  jets  thus  shown  were  obtained  under  the  same  con- 
ditions, except  that  the  speed  of  the  engine  for  Fig.  37  was  25 
miles;  for  Fig.  38,  35  miles,  and  for  Fig.  39,  45  miles  per  hour. 
The  conditions  of  running  were  such  that  each  increment  of 
speed  resulted  in  a  larger  volume  of  steam  delivered,  and  con- 
sequently in  a  higher  vacuum.  The  diagrams  show  that  as 
the  volume  of  steam  delivered  increases,  the  velocity  of  the 
jet  increases  and  its  spread  diminishes,  due,  doubtless,  to  the 


ACTION  Of    THE  EXHAUST-JET. 


77 


FIG.  36. 


7*  LOCOMOTIVE  SPARKS. 

reaction  of  the  body  of  smoke-box  gases  surrounding  the  jet. 
The  velocity  curves  which  in  Fig.  38  are  pretty  evenly  dis- 
tributed throughout  the  body  of  the  jet  are  in  Fig.  39  crowded 
together,  giving  evidence  in  the  latter  case  of  a  very  dense  and 
powerful  jet. 

The  results  derived  from  a  large  number  of  experiments 
similar  in  nature  to  that  just  described  will  be  found  presented 


MILES  PER  HOUR  25 

REVOLUTIONS  PER  MINUTE  135 

POUNDS  CF  STEAM  PER  HOUR     6090 


MILES  PER  HOUR 

REVOLUTIONS  PER  MINUTE  T88/ 

POUNDS  OF  STEAM  PER  HOUR     8122^, 


MILES  PER  HOUR  43 

REVOLUTIONS  PER  MINUTE  242 

POUNDS  OF  STEAM  PER  HOUR     8670 


FIG.  37. 


FIG.  38. 


FIG.  39. 


in  the  Proceedings  which  have  been  referred  to.  From  their 
study  the  following  conclusions  concerning  the  action  of  the 
jet  appear  to  have  been  justified. 


ACTION  OF   THE  EXHAUST-JET,  79 

29.  The  Action  of  the  Exhaust-jet.  —  Previous  to  the 
experiments  just  described  it  had  usually  been  assumed  that 
the  action  of  the  exhaust-jet  is  similar  to  that  of  a  pump ;  that 
each  exhaust  supplies  a  ball  of  steam,  which  fills  the  stack 
A^ery  much  as  the  piston  of  a  pump  fills  its  cylinder,  and  which 
pushes  before  it  a  certain  volume  of  the  smoke-box  gases  until 
it  passes  out  at  the  top  of  the  stack.  The  experiments  dis- 
prove this  theory.  They  show  that  the  jet  of  steam  does  not 
fill  the  stack  at  or  near  the  bottom ;  that  under  certain  condi- 
tions common  to  practice  it  touches  the  stack  only  when  it  is 
very  near  the  top;  and,  finally,  that  a  jet  of  steam  flowing 
steadily  from  the  exhaust-tip,  the  engine  being  at  rest,  results 
in  draft  conditions  which  are  in  every  way  similar  with  those 
obtained  with  the  engine  running,  the  same  amount  of  steam 
being  discharged  per  unit  of  time  in  each  case. 

Enough  has  not  yet  been  done  to  define  the  precise  action 
of  the  jet,  but  it  may  be  said  with  certainty  (i)  that  it  acts  to 
induce  motion  in  the  particles  of  gas  which  immediately  sur- 
round it,  and  also  (2)  that  it  acts  to  enfold  and  entrain  the 
gases  which  are  thus  made  to  mingle  with  the  substance  of  the 
jet  itself. 

The  induced  action,  which,  for  the  jets  experimented  upon, 
is  by  far  the  most  important,  may  be  illustrated  by  means  of 
Fig.  40.  The  arrows  in  this  figure  represent,  approximately, 
the  direction  of  the  currents  surrounding  the  jets.  It  will  be 
seen  that  the  smoke-box  gases  tend  to  move  toward  the  jet, 
and  not  toward  the  base  of  the  stack,  at  which  point  they  are 
to  leave  the  smoke-box.  That  is,  the  jet,  by  virtue  of  its  high 
velocity  and  by  its  contact  with  surrounding  gases,  gives 
motion  to  particles  close  about  it,  and  these,  moving  on  with 
the  jet,  make  room  for  other  particles  which  are  farther  away. 
As  the  enveloping  shell  of  gas  approaches  the  top  of  the  stack, 


So 


LOCOMOTIVE  SPARKS. 


FIG.  40. 


ACTION  OF   THE  EXHAUST-JET.  Si 

its  velocity  increases  and  it  becomes  thinner  and  thinner,  all 
as  shown  by  Fig.  40.  All  parts  of  the  jet  require  gases  to 
work  upon  the  upper  as-  well  as  the  lower  part.  Gages 
attached  to  the  side  of  the  stack  show  a  vacuum,  because  the 
gases  needed  for  the  upper  portion  of  the  jet  can  reach  it  only 
by  coming  in  around  the  jet  lower  down.  In  other  words,  the 
action  of  the  upper  part  of  the  jet  induces  a  vacuum  in  the 
lower  part  of  the  stack,  just  as  the  action  of  the  jet  as  a  whole 
induces  a  vacuum  in  the  smoke-box.  It  will  be  shown  later 
that  as  the  amount  of  work  to  be  done  by  the  exhaust  is 
increased  the  jet  becomes  smaller,  thus  making  room  for 
larger  volumes  of  gas  to  pass  between  it  and  the  stack ;  the 
velocity  both  of  the  jet  and  of  the  induced  currents  increasing. 

The  Intermingling  of  tJie  Smoke-box  Gases  ivit/i  tJie  Steam. 
That  there  is  some  intermingling  of  the  smoke-box  gases  with 
the  steam  of  the  jet  is  made  evident  by  the  appearance  of  the 
combined  stream  as  it  issued  from  the  top  of  the  stack.  The 
manner  in  which  this  intermingling  takes  place  will  be  seen 
from  the  following  considerations. 

Any  stream  flowing  from  a  nozzle  through  a  resisting 
medium  will  have  a  higher  velocity  at  its  centre  than  at  its 
circumference  or  sides.  That  is,  the  particles  at  the  centre  of 
the  jet  move  at  a  higher  velocity  than  those  on  the  outside,  the 
latter  being  held  back  by  contact  with  the  surrounding  gas. 
The  result  of  the  different  velocities  in  the  same  stream  is  a 
wave  motion  of  the  individual  particles  of  which  the  stream  is 
composed.  Thus  the  path  of  any  one  of  these  particles  may 
be  shown  by  Fig.  41,  A,  but  the  exact  form  and  frequency  of 
the  loops  will  depend  upon  the  relation  between  these  differ- 
ences in  the  velocity  of  particles  in  different  portions  of  the 
stream,  and  the  actual  mean  velocity  of  the  jet.  If  the  velocity 
of  the  jet  is  high,  and  differences  for  different  portions  of  the 


LOCOMOTIVE  SPARKS. 


cross-section  are  not  great,  the  loop  may  disappear,  the  path 
appearing  as  shown  by  Fig.  41,  B.  With  a  still  higher  mean 
velocity,  and  a  smaller  difference,  the  loops  would  approach 


FIG.  41. 

the  form  shown  by  Fig.  41,  C.  The  exhaust-jet  appears  to 
take  this  latter  form.  Measurements  to  determine  its  velocity 
show  that  particles  in  the  centre  move  much  more  rapidly  than 
those  near  the  outside,  and  other  measurements  to  determine 


Fio.   42. 


ACTION   OF   THE  EXHAUST-JET.  85 

the  form  of  the  jet  as  a  whole,  define  a  boundary  which  is 
neither  a  straight  line  nor  a  regular  curve,  but  which  agrees 
closely  with  the  form  given  by  Fig.  41,  .C.  All  this  shows 
that  the  jet  is  stepped  off  in  nodes,  which  under  given  condi- 
tions remain  fixed  in  position.  This  conclusion,  based  upon 
measurements  of  the  jet,  is  confirmed  by  the  appearance  of  the 
jet  as  seen  in  an  engine  running  with  the  front-end  open. 
The  jet  when  thus  viewed  exhibits  one  or  more  bright  spots 
which  remain  in  a  fixed  position.  It  is  through  the  wave  action 
of  the  particles  making  up 'the  steam-jet  that  the  surrounding 
gases  are  enfolded  and  intermixed  with  the  steam  of  the  jet. 

It  is  clear  that  any  design  of  nozzle  which  will  serve  to 
subdivide  the  stream,  or  to  spread  it  so  as  to  increase  its  cross- 
section,  will  assist  the  jet  in  its  effort  to  entrain  the  gases,  but 
it  is  not  clear  that  there  is  any  gain  in  efficiency  to  be  realized 
in  such  a  result.  It  is  possible  that,  as  the  mixing  action  is  in- 
creased, the  induced  action  may  be  diminished,  and  that  the 
sum  total  of  the  effect  produced  may  remain  nearly  constant. 
The  work  which  has  thus  far  been  done  is  not  conclusive  on 
this  point,  but  the  evidence  tends  to  show  that  the  more  com- 
pact and  dense  the  jet  the  higher  its  efficiency.  It  is  certainly 
clear  that,  for  the  jets  experimented  upon,  the  mixing  action  is 
hardly  more  than  incidental  to  the  induced  action,  the  latter 
constituting  the  influence  through  which  the  work  of  the  jet  is 
chiefly  accomplished. 

In  connection  with  the  diagrams  Figs.  37  to  39,  Fig.  42, 
which  is  from  a  photograph  of  the  jet  delivered  from  a  double 
nozzle,  will  be  of  interest.  The  view  represents  what  one  sees 
when  looking  into  a  front-end  when  the  locomotive  is  being 
run  with  the  front  door  open. 

30.  Distribution  of  Sparks  within  the  Stack. — Designers 
of  draft  appliances,  being  confronted  with  the  problem  of  inter- 


86 


LOCOMOTIVE  SPARKS. 


cepting  the  sparks  at  some  point  between  the  front  tube-sheet 
and  the  top  of  the  stack,  will  be  helped  in  this  work  by  a 
knowledge  of  the  course  taken  by  the  sparks.  It  is  thought 
proper,  therefore,  to  make  of  record  such  information  upon  this 
point  as  has  been  derived  from  certain  investigations,  some 
features  of  which  have  already  been  discussed.  For  the  pur- 
pose of  such  a  presentation  the  data  as  obtained  for  Test 
No.  4,  Table  I,  Chapter  III,  have  been  selected  as  fairly  repre- 
sentative of  the  general  conditions. 

Sparks  passing  through  a  square-inch  section  of  the  stack 
at  various  points  are  indicated  in  position  and  value  by  the 


POUNDS  OF  SPARKS  PASSING  OUT  OF  STACK  PER 

SQUARE  INCH  OF  STACK  AREA  PER  KOUR  AT  THE 

VARIOUS  PLACES  DESIGNATED-     THE  TWO  FULL 

CIRCLES  INDICATE  THE  SIZE  AND  LOCATION 

OF  THE  DOUBLE  EXHAUST-TIP. 

FIG.  43- 

numerals  given  in  Fig.  43.  It  will  be  seen  that  the  weight 
diminishes  steadily  as  the  positions  of  observation  are  changed 
from  the  outside  to  points  nearer  the  centre,  and  also  that 
those  points  which  are  most  remote  from  the  action  of  the 
exhaust-jet  show  the  largest  weight  of  sparks.  Fig.  44  gives 
the  weight  of  sparks  per  hour  for  the  several  annular  rings  into 


ACTION  OF  THE  EXHAUST-JET.  87 

which  the  area  of  the  stack  is  assumed  to  be  divided;  the 
breadth  of  each  ring  being  2  inches.  Here,  again,  the  fact 
that  the  sparks  follow  the  wall  of  the  stack  rather  than  the 
centre  of  the  stream  is  disclosed;  more  than  50  per  cent  of  the 


POUNDS  OF  SPARKS  PASSING  OUT  OF 
STACK'PER  HOUR  IN  THE  SEVERAL 
AREAS  INDICATED. 

FIG.  44. 


FIG.  45. 

whole  weight  being  credited  to  an  area  embraced  by  a  ring 
2  inches  broad  measured  from  the  outside  circumference  of  the 


88  LOCOMOTIVE  SPARKS. 

stream.  The  distribution  of  sparks  in  the  stack  is  shown 
graphically  by  Fig.  45.  This  figure  may  be  accepted  as  a 
correct  graphical  presentation  of  the  comparative  density  of 
the  sparks  throughout  all  portions  of  the  cross-section  of  the 
stack. 

The  conclusion  concerning  distribution  is  that  the  sparks 
follow  most  readily  those  portions  of  the  stream  issuing  from 
the  stack  which  have  the  lowest  velocity,  which  conclusion  is 
entirely  consistent  with  the  information  already  presented  re- 
garding the  action  of  the  exhaust-jet.  It  should  be  noted, 
however,  that  these  observations  were  made  on  a  cross-section 
of  the  stream  at  a  point  immediately  after  it  issued  from  the 
stack,  and  may  not  represent  conditions  actually  existing  in 
the  stack. 


CHAPTER    VI. 

SPREAD  OF  SPARKS  FROM  LOCOMOTIVES  AS  DISCLOSED 
BY   OBSERVATIONS   ALONG   THE    RIGHT-OF-WAY. 

THE  preceding  chapters  have  served  to  show  that  all  loco- 
motives when  working  under  normal  conditions  discharge 
particles  of  ash  and  fuel  from  the  top  of  their  stacks.  It  has 
been  shown  that  the  fuel-value  of  the  material  thus  discharged 
is  considerable.  We  are  now  to  consider  what  is  the  distribu- 
tion of  the  material  discharged  over  the  surface  of  the  ground 
in  the  immediate  vicinity  of  the  track,  and  what  liability  there 
is  of  fire  arising  from  its  presence. 

31.  Experiments  and  Results. — To  secure  information 
covering  this  point,  investigations  under  the  direction  of  the 
author  were  first  undertaken  by  Mr.  George  F.  Mug,  M.E.,* 
who  made  observations  both  at  the  Purdue  experimental  loco- 
motive and  along  the  right-of-way.  While  Mr.  Mug  obtained 
much  valuable  data,  his  efforts  were  largely  given  to  the 
developments  of  methods  of  procedure.  In  this  he  was  so 
successful  that  subsequent  investigations  have  been  based  upon 
his  work.  The  most  elaborate  data  thus  far  obtained  are  those 
of  Messrs.  Ducas  and  Dill,  from  whose  thesis  t  the  facts  of  this 
chapter  are  chiefly  drawn. 

*  "  A  Study  of  the  Cinder-  and  Spark-losses  in  Locomotives,"  a  thesis 
by  George  F.  Mug,  B.S.,  candidate  for  the  degree  of  M.E.,  Purdue 
University,  June,  1896. 

f  "  Spark-losses  from  Locomotives  on  the  Road,"  a  thesis  by  J.  B. 
Dill  and  Charles  Ducas,  candidates  for  the  degree  of  B.S.,  Purdue  Uni- 
versity, June,  1900. 

8q 


9o 


LOCOMOTIVE  SPARKS. 


The  method  employed  may  be  described  as  follows  :  ten 
metal  pans  22  inches  square  were  placed  in  line  at  right  angles 


FIG.  46. 

to  the  track  from  10  to  100  feet  apart,  and  on  the  leeward  side, 
all  as  indicated  by  Fig.  46.  The  exact  distance  of  each  pan 
from  the  centre  of  the  track  is  shown  by  Table  V,  and  a  view  of 
the  field  with  the  pans  in  position  by  Fig.  47.  The  pans  were 
placed  on  one  side  or  the  other  of  the  track,  depending  upon 


FIG.  47. 


TABLE  V. 


Number  of  Test. 

Distances  of  Pans  from  Centre  of  Track  in  Feet. 

I     2     3       

15 

20 
2O 

25 

35 
40 

35 
50 
60 

45 
65 
80 

70 
80 

IOO 

IOO 
IOO 

125 

150 
125 
1  60 

2OO 

175 

2OO 

250 
250 
250 

350 
350 

350 

4n    6    7    8    o 

TO     II     12     17     IJ.. 

SPREAD   OF  SPARKS  FROM  LOCOMOTIVES. 


93 


whether  the  wind  was  from  the  north  or  the  south.  A  layer  of 
cotton  in  the  bottom  of  each  pan  served  to  retain  sparks  which 
otherwise  might  have  been  blown  away  by  the  wind,  and  was 
expected  to  indicate  by  a  scorched  mark  the  degree  of  heat  in 
the  spark.  The  place  selected  for  conducting  the  tests  was  at 
the  top  of  a  grade  on  the  Lake  Erie  &  Western  Railroad,  at  a 
point  about  two  miles  west  of  the  Lafayette  station.  A  profile 
of  the  road  in  this  vicinity  is  given  as  Fig.  48.  The  section  of 
track  involved  is  used  jointly  by  the  L.  E.  &  W.  R.  R.  and  by 
the  Big  Four  Company,  all  Indianapolis  and  Chicago  trains  of 


370. 


360. 


365. 
FIG.  48. 

the  latter  company  passing  over  it.  It  is  to  be  noted  that, 
from  the  start  at  the  station,  locomotives  have  a  heavy  pull  all 
the  way  to  the  point  where  the  observations  were  made,  with 
heavy  grades  still  beyond.  They  were  therefore  invariably 
working  very  hard  when  passing  the  point  of  observation. 
Observations  were  made  only  on  those  trains  which  came  up 
the  grade.  When  others  passed  the  pans  were  covered. 

The  observations  were  such  as  served  to  make  of  record 
the   direction   of  wind,   velocity  of  wind,   temperature  of  the 


94  LOCOMOTIVE  SP4RKS. 

atmosphere,  character  of  train  (whether  freight  or  passenger), 
number  of  cars  in  train,  time  required  to  pass  between  two 
stakes  set  at  a  known  distance  apart,  type,  name  and  number 
of  locomotive,  and  character  of  smoke  (light,  dark,  very  dark, 
or  black).  From  the  observed  time  in  passing  between  the 
two  stakes  the  speed  of  the  train  was  calculated.  A  photo- 
graph of  each  train  was  also  taken.  After  the  train  had  passed, 
all  the  sparks  caught  in  each  pan  were  carefully  collected, 
placed  in  a  separate  bottle,  and  properly  labelled. 

Table  VI  presents  a  summary  of  the  general  observations 
obtained  during  the  progress  of  the  tests.  It  is  to  be  noted 
that  most  of  the  freight  trains  were  run  with  a  "  pusher  "  in 
the  rear,  and  the  sample  sparks  collected  represent  the  dis- 
charge from  two  engines.  The  tests  include  conditions  for 
which  the  wind  velocities  varied  from  a  little  over  five  miles 
per  hour  to  nearly  twelve  miles  per  hour. 

The  weight  of  sparks  caught  in  each  pan  for  each  test,  as 
well  as  the  weight  falling  upon  an  area  of  10  X  10  feet  for 
which  each  pan  is  the  geometrical  centre,  as  calculated  from 
the  weight  collected  in  the  pan,  is  given  in  Tables  VII  and 
VIII.  All  weights  are  in  grammes.  From  the  fourteen 
different  tests  which  were  made,  six  have  been  selected  as 
typical,  to  be  made  the  subject  of  a  more  detailed  description. 
The  results  of  these  fairly  represent  the  whole  series.  They 
are  so  selected  as  to  include  the  full  range  of  conditions  which 
were  obtained.  The  collection  from  each  pan  for  the  six  tests 
selected  is  shown  in  detail  in  pages  1 10  to  127.  The  sketches 
represent  the  actual  size  and  shape  of  all  the  sparks  caught  in 
each  pan  for  the  several  tests  under  consideration.  Tests 
Nos.  2  and  10  are  those  for  which  the  spread  of  sparks  is 
greatest ;  Tests  Nos.  5  and  6,  those  for  which  it  is  of  average 
extent;  and  Tests  Nos.  8  and  14,  those  for  which  it  is  least. 
In  Tests  Nos.  2  and  10  the  greatest  weight  of  sparks  is  found 


SPREAD   OF  SPARKS   FROM   LOCOMOTIVES. 


95 


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Test  Number. 

Distance  of  pans  from 
centre  of  track.  Feet. 
Weight  of  sparks  caught 
in  each  pan.  Grammes. 
Equivalent  weight  of 
sparks  per  100  square 
feet.  Grammes  

Test  Number. 

Distance  of  pans  from 
centre  of  track.  Feet. 
Weight  of  sparks  caught 
in  each  pan.  Grammes 
Equivalent  weight  of 
sparks  per  100  square 
feet.  Grammes....  .  .. 

Test  Number. 

Distance  of  pans  from 
centre  of  track.  Feet 
Weight  of  sparks  caught 
in  each  pan.  Grammes 
Equivalent  weight  of 
sparks  per  100  square 
feet.  Grammes  

Test  Number. 

Distance  of  pans  from 
centre  of  track.  Feet. 
Weight  of  sparks  caught 
in  each  pan.  Grammes 
Equivalent  weight  of 
sparks  per  100  square 
feet.  Grammes  

SPREAD  OF  SPARKS  FROM  LOCOMOTIVES* 


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Test  Number. 

Distance  of  pans  from 
centre  of  tr^.ck.  Feet. 
Weight  of  sparks  caught 
in  each  pan.  Grammes 
Equivalent  weight  of 
sparks  per  100  square 
feet.  Grammes  

Test  Number. 

Distance  of  pans  from 
centre  of  track.  Feet. 
Weight  of  sparks  caught 
in  each  pan.  Grammes 
Equivalent  weight  of 
sparks  per  100  square 
feet.  Grammes  

Test  Number. 

Distance  of  pans  from 
centre  of  track.  Feet. 
Weight  of  sparks  caught 
in  each  pan.  Grammes 
Equivalent  weight  of 
sparks  per  100  square 
feet.  Grammes  

!?: 


98  LOCOMOTIVE  SPARKS. 

at  70  and  80  feet  from  the  track,  respectively;  in  Tests  Nos. 
5  and  6  the  greatest  weight  is  found  at  50  and  65  feet,  re- 
spectively; and  in  Tests  Nos.  8  and  14  the  greatest  weight  is 
at  20  and  40  feet,  respectively. 

It  will  be  of  little  value  to  attempt  to  compare  one  test 
with  another,  even  though  the  conditions  as  to  wind  may  be 
apparently  the  same.  Such  a  comparison  would  only  lead  to 
flagrant  inconsistencies.  It  will  be  shown  in  a  subsequent 
chapter  that  the  distance  traversed  by  a  spark  after  leaving 
the  stack  is  dependent  in  part  on  the  initial  upward  impulse 
received.  This  in  turn  is  dependent  on  conditions  within  the 
locomotive  itself,  and  concerning  which  no  information  could 
be  made  of  record.  It  is,  therefore,  but  reasonable  to  expect 
that  even  under  like  conditions  of  wind  the  distribution  of 
sparks  for  individual  tests  may  be  widely  different,  and  the 
results  show  that  such  a  condition  actually  exists. 

To  better  show  the  distribution  of  sparks,  the  weight 
caught  in  each  pan  for  each  of  the  six  typical  tests  is  shown 
graphically  by  Figs.  50,  52,  54,  56,  58,  and  59. 

In  connection  with  the  diagrams,  photographs  of  the  head 
of  the  several  trains  involved  by  the  tests  are  given  as  Figs. 
49>  5J>  53 '  55'  an<^  57'  eacn  of  the  six  tests  being  represented 
excepting  No.  8,  for  which  the  photograph  failed.  The  photo- 
graphs indicate  something  of  the  heavy  service  which  the 
locomotives  were  performing,  also  something  of  the  direction 
and  velocity  of  the  wind.-  It  would  seem  that  the  total  weight 
of  sparks  discharged  by  the  locomotives  shown,  under  the 
conditions  which  have  been  described,  must  have  been  nearly 
maximum  for  any  locomotive  in  good  condition.  With  higher 
wind  velocities  the  sparks  might  be  spread  over  somewhat 
greater  distances,  but  it  is  hardly  likely  that  they  would  ever 
be  more  thickly  strewn  or  that  the  relation  of  size  to  distance 
from  track  would  be  greatly  changed. 


SPARK-LOSSES    FROM    LOCOMOTIVES    ON    THE    ROAD. 
TEST    NO.    2.       TRAIN    WITH    "PUSHER." 


FIG.  49. — One    of    the    two    locomotives    during    the    test,  the    record  for 
which  is  given  below. 


25   50   75 


100  125  150  175  200  225  350  275  300 

DISTANCES  OF  PANS  FROM  TRACK  IN  FEET. 

FIG.  50. 


325      350 


99 


SPARK-LOSSES    FROM    LOCOMOTIVES    ON    THE    ROAD. 
TEST    NO.  10.     TRAIN    WITH    l<  PUSHER." 


FIG.  51. — One   of   the   two  locomotives   during  the    test,    the    record    for 
which  is  given  below. 


50   75   100  125   150  175  300   225  350  875   300  385  350 

INSTANCES   OF   PANS    FROM   TRACK   IN    FEET, 


FIG.  52. 


101 


SPARK-LOSSES    FROM    LOCOMOTIVES    ON    THE    ROAD. 
TEST   NO.  5.      TRAIN   WITH    "PUSHER." 


FIG.   53. — One    of   the    two   locomotives   during    the    test,  the  record  for 

which  is  given  below. 


25   60 


75   100  125  150  175  200  225  250  275 

DISTANCES    OF    PANS    FROM   TRACK    IN    FEET. 

FIG.  54- 


325     350 


103 


SPARK-LOSSES    FROM    LOCOMOTIVES  ON    THE    ROAD. 
TEST    NO.  6. 


FK;>   55 — The  locomotive  during  the  test,  the  record  for  which  is  given 

below. 


25       50 


75      100     125     150      175     200     225      250     275      300     325      360 

DISTANCES   OF   PANS    FROM   TRACK    IN    FEET. 


FIG.  56. 


105 


SPARK-LOSSES    FROM    LOCOMOTIVES    ON    THE    ROAD. 
TEST    NO.  14.      TRAIN    WITH    "PUSHER." 


FiG.   57.— One    of    the    two   locomotives    during  the  test,    the    record 
which  is  given  below. 


for 


25       50 


75      100     125      150     175      200     225     250     275     300 
DISTANCES   O.F   BANS    FROM  TRACK   IN   FEET. 

FIG.  58. 


325      350 


107 


SPARK-LOSSES    FROM    LOCOMOTIVES    ON    THE   ROAD. 
TEST    NO.  8. 

The  photograph  for  this  test  failed.     The  following  is  a 
summary  of  the  conditions  which  prevailed: 

Number  of  locomotives I 

Type  of  locomotive Mogul 

Number  of  freight-cars 12 

Speed  of  train,  miles  per  hour 21.6 

Velocity  of  wind,  miles  per  hour 7 

Character  of  smoke .  .  dark 


\ 


75      100      125      150     175     200     225     250     275 

DISTANCES   OF   PANS    FROM  TRACK   IN    FEET. 


FIG.  59- 


300     325      350 


109 


110 


LOCOMOTIVE  SPARKS. 


SPARKS  FROM  TEST  No.  2. 

THIS  test  and  Test  No.  10,  the  results  of  which  follow,  are 
typical  of  those  tests  in  which  the  heaviest  fall  of  sparks  is 
found  at  the  greatest  distance  from  the  track.  The  spots 
within  each  rectangle  show  the  number  and  actual  size  of 
sparks  collected  in  each  pan.  The  rectangle  does  not  indicate 
the  size  of  the  pan,  which  was  22  inches  square. 

The  sparks  collected  include  those  deposited  by  the 
locomotive  at  the  head  of  the  train  (Fig.  49)  and  by  the 
4 'pusher  "  at  its  rear. 

Speed  of  train 15.7  miles  per  hour 

Velocity  of  wind 1 1.6  miles  per  hour 

Number  of  freight-cars 29 

15 


Actual  size  and  number  of 
.sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance 
of  75  feet  from  the  centre  of  the 
track. 


2 


25 


Actual  size  and  number  of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance 
of  25  feet  from  the  centre  of  the 
track. 


SPREAD   OF  SPARKS  FROM  LOCOMOTIVES.  ill 

SPARKS  FROM  TEST  No.   2. — Continued. 


Actual  size  and  number  of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance 
of  35  feet  from  the  centre  of  the 
track. 


Actual  size  and  number  of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance 
of  45  feet  from  the  centre  of  the 
track. 


Actual  size  and  number  of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance 
of  jo  feet  from  the  centre  of  the 
track. 


Actual  size  and  number  of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance 
of  100  feet  from  the  centre  of  the 
track. 


45 


70 


too 


„•••: ., 

•**»!> 


<a  9    <* 

i   ***  ^^k,  «  ^rf    *          4 

VMi-^v 

1k>  ^^  •   i,      ^          * 

,*f  •  »•       .    •     „  4>  Wifl  .    «T      a 


112 


LOCOMOTIVE  SPARKS. 


SPARKS  FROM  TEST  No.  2. — Continued. 

150 


Actual  size  and  number  of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance 
of  150  feet  from  the  centre  of  the 
track. 


Actual  size  and  number  of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance 
of  200  feet  from  the  centre  of  the 
track. 


Actual  size  and  number  of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance 
of  250  feet  from  the  centre  of  the 
track. 


Actual    size    and   number   of 
sparks  falling  within  an  area  of 
484  square  inches  at  a  distance    ~ 
°f  35°  feet  from  the  centre  of  the 
track. 


200 


. « •*  • 

•   *  •  y.  ' 


250 


350 


SPREAD  OF  SPARKS  FROM  LOCOMOTIVES. 


SPARKS  FROM  TEST  No.  10. 


THIS  test  and  Test  No.  2,  the  results  of  which  are  given 
on  preceding  pages,  are  typical  of  those  tests  in  which  the 
heaviest  fall  of  sparks  is  found  at  the  greatest  distance  from  the 
track.  The  spots  within  each  rectangle  show  the  number  and 
actual  size  of  sparks  collected  in  each  pan.  The  rectangle  does 
not  indicate  the  size  of  the  pan,  which  was  22  inches  square. 

The  sparks  collected  include  those  deposited  by  the 
locomotive  at  the  head  of  the  train  (Fig.  51)  and  by  the 
' '  pusher  ' '  at  its  rear. 

Speed  of  train 14.9  miles  per  hour 

Velocity  of  wind 7.9  miles  per  hour 

Number  of  freight-cars 34 


Actual  size  and  number  of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance 
of  20  feet  from  the  centre  of  the 
track. 


Actual  size  and  number  of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance 
of  4.0  feet  from  the  centre  of  the 
track. 


10 


40 


114  LOCOMOTIVE  SPARKS. 

SPARKS  FROM  TEST  No.  10. — Continued. 


Actual  size  and  number  of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance 
of  60  feet  from  the  centre  of  the 
track. 


Actual  size  and  number  of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance 
of  80  feet  from  the  centre  of  the 
track. 


Actual  size  and  number  of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance 
of  100  feet  from  the  centre  of  the 
track. 


Actual  size  and  number  of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance 
of  125  feet  from  the  centre  of  the 
track. 


10 


*  v 


',  »«•** 


so 


10 


+ 


too 


125 


SPREAD   OF  SPARKS  FROM  LOCOMOTIVES. 


SPARKS  FROM  TEST  No.   10. — Continued. 

160 


Actual  size  and  number  of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance 
of  160  feet  from  the  centre  of  the 
track. 


Actual  size  and  number  of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance 
of  200  feet  from  the  centre  of  the 
track. 


Actual  size  and  number  of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance 
of  250  feet  from  the  centre  of  the 
track. 


10 


10 


10 


Actual  size  and  number  of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance 
of  350  feet  from  the  centre  of  the 
track. 


200 


250 


350 


n6 


LOCOMOTIVE  SPARKS. 


SPARKS  FROM  TEST  No.  5. 

THIS  test  and  Test  No.  6,  the  results  of  which  follow,  are 
typical  of  those  tests  in  which  the  heaviest  fall  of  sparks  is 
found  at  a  moderate  distance  from  the  track.  The  spots  within 
each  rectangle  show  the  number  and  actual  size  of  sparks  col- 
lected in  each  pan.  The  rectangle  does  not  indicate  the  size 
of  the  pan,  which  was  22  inches  square. 

The  sparks  collected  include  those  deposited  by  the 
locomotive  at  the  head  of  the  train  (Fig.  53)  and  by  the 
' '  pusher  ' '  at  the  rear. 

Speed  of  train 15.1  miles  per  hour 

Velocity  of  wind 8.7  miles  per  hour 

Number  of  freight-cars 34 

20 


Actual    size   and   number    of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance     5 
of  20  feet  from  the  centre  of  the 
track. 


. 


35 


Actual   size   and    number    of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance      _ 
of  35  feet  from  the  centre  of  the 
track. 


SPREAD   OF  SPARKS  FROM  LOCOMOTIVES. 


117 


SPARKS  FROM  TEST  No.   5. — Continued. 

50 


Actual  size  and  number  of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance 

9 

of  50  feet  from  the  centre  of  the 
track. 


Actual  size  and  number  of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance 
of  65  feet  from  the  centre  of  the 
track. 


Actual   size    and    number    of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance     5 
of  80  feet  from  the  centre  of  the 
track. 


Actual  size  and  number  of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance 
of  100  feet  from  the  centre  of  the 
track. 


65 


80 


100 


n8 


LOCOMOTIVE  SPARKS. 


SPARKS  FROM  TEST  No.  5. — Continued. 

125 


Actual   size   and    number    of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance     5 
of  125  feet  from  the  centre  of  the 
track. 


Actual   size   and    number   of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance    5 
of  775  feet  from  the  centre  of  the 
track. 


Actual   size    and    number   of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance    r- 
of  250  feet  from  the  centre  of  the 
track. 


Actual    size  and   number    of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance     ,. 
°f  35°  feet  from  the  centre  of  the 
track. 


175 


250 


350 


SPREAD   OF  SPARKS  FROM  LOCOMOTIVES. 


119, 


SPARKS  FROM  TEST  No.  6. 

THIS  test  and  Test  No.  5,  the  results  of  which  are  given 
on  preceding  pages,  are  typical  of  those  tests  in  which  the 
heaviest  fall  of  sparks  is  found  at  a  moderate  distance  from  the 
track.  The  spots  within  each  rectangle  show  the  number  and 
actual  size  of  sparks  collected  in  each  pan.  The  rectangle  does 
not  indicate  the  size  of  the  pan,  which  was  22  inches  square. 

The  sparks  collected  are  those  deposited  by  a  single 
locomotive  (Fig.  55)  at  the  head  of  a  train. 

Speed  of  train 23.3  miles  per  hour 

Velocity  of  wind 9.8  miles  per  hour 

Number  of  freight-cars 1 1 


Actual  size  and  number  of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance 
of  20  feet  from  the  centre  of  the 
track. 


Actual  size  and  number  of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance 
of  35  feet  from  the  centre  of  the 
track. 


35 


120 


LOCOMOTIVE  SPARKS. 


SPARKS  FROM  TEST  No.  6. — Continued. 

50 


Actual  size  and  number  of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance 
of  50  feet  from  the  centre  of  the 
track. 


Actual   size   and    number    of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance     « 
of  65  feet  from  the  centre  of  the 
track. 


Actual  size  and  number  of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance 
of  80  feet  from  the  centre  of  the 
track. 


Actual  size  and  number  of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance 
of  100  feet  from  the  centre  of  the 
track. 


65 


' 


100 


SPREAD   OF  SPARKS   FROM   LOCOMOTIVES. 


121 


SPARKS  FROM  TEST  No.  6. — Continued. 

125 


Actual  size  and  number  of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance 
of  125  feet  from  the  centre  of  the 
track. 


Actual  size  and  number  of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance 
of  775  feet  from  the  centre  of  the 
track. 


Actual  size  and  number  of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance 
of  250  feet  from  the  centre  of  the 

track. 


Actual  size  and  number  of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance 
of  350  feet  from  the  centre  of  the 
track. 


115 


250 


r. 


350 


122 


LOCOMOTIVE  SPARKS. 


SPARKS  FROM  TEST  No.  8. 

THIS  test  and  Test  No.  14,  the  results  of  which  follow,  are 
typical  of  those  tests  in  which  the  heaviest  fall  of  sparks  is 
found  near  to  the  track.  The  spots  within  each  rectangle  show 
the  number  and  actual  size  of  sparks  collected  in  each  pan. 
The  rectangle  does  not  indicate  the  size  of  the  pan,  which  was 
22  inches  square. 

The  sparks  collected  were  from  a  single  locomotive  at  the 
head  of  the  train. 

Speed  of  train 21.6  miles  per  hour 

Velocity  of  wind 7  miles  per  hour 

Number  of  freight-cars 12 


20 


Actual  size  and  number  of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance 
of  20  feet  from  the  centre  of  the 
track. 


35 


Actual  size  and  number  of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance 

o 

°f 35  feet  from  the  centre  of  the 
track. 


SPREAD  OF  SPARKS  FROM  LOCOMOTIVES. 


123 


SPARKS  FROM  TEST  No.   8. — Continued. 


Actual  size  and  number  of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance 
of  50  feet  from  the  centre  of  the 
track. 


Actual  size  and  number  of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance 
of  65  feet  from  the  cencre  of  the 
track. 


Actual  size  and  number  of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance 
of  80  feet  from  the  centre  of  the 
track. 


Actual  size  and  number  of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance 
of  100  feet  from  the  centre  of  the 
track. 


50 


65 


'•*- '  < ' 


80 


100 


. 


I24 


LOCOMOTIVE  SPARKS. 


SPARKS  FROM  TEST  No.  8. — Continued. 

125 


Actual  size  and  number  of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance 
of  125  feet  from  the  centre  of  the 
track. 


Actual  size  and  number  of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance 
of  775  feet  from  the  centre  of  the 
track. 


Actual    size   and   number    of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance      ~ 
of  250  feet  from  the  centre  of  the 
track. 


Actual  size  and  number  of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance 
of  350  feet  from  the  centre  of  the 
track. 


175 


250 


350 


SPREAD  OF  SPARKS  FROM  LOCOMOTIVES. 


125 


SPARKS  FROM  TEST  No.  14. 

THIS  test  and  Test  No.  8,  the  results  of  which  are  given 
on  preceding  pages,  are  typical  of  those  tests  in  which  the 
heaviest  fall  of  sparks  is  found  near  to  the  track.  The  spots 
within  each  rectangle  show  the  number  and  actual  size  of 
sparks  collected  in  each  pan.  The  rectangle  does  not  indicate 
the  size  of  pan,  which  was  22  inches  square. 

The  sparks  collected  include  those  deposited  by  the 
locomotive  at  the  head  of  the  train  (Fig.  57)  and  by  its 
* '  pusher  ' '  at  the  rear. 

Speed  of  train 18.3  miles  per  hour 

Velocity  of  wind 8.9  miles  per  hour 

Number  of  freight-cars 30 

20 


Actual  size  and  number  of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance 
of  20  feet  from  the  centre  of  the 
track. 


40 


Actual    size   and   number    of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance     - 
of  4.0  feet  from  the  centre  of  the 
track. 


126 


LOCOMOTIVE  SPARKS. 


SPARKS  FROM  TEST  No.   14. — Continued. 

60 


Actual  size  and  number  of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance 
of  60  feet  from  the  centre  of  the 
track. 


Actual  size  and  number  of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance 
of  80  feet  from  the  centre  of  the 
track. 


Actual  size  and  number  of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance 
of  100  feet  from  the  centre  of  the 
track. 


Actual    size    and   number   of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance    i 
of  125  feet  from  the  centre  of  the 
track. 


80 


100 


• 


*!**;:-v 

fo?v\:: 
*•>/:' 


125 


SPREAD   OF  SPARKS  FROM  LOCOMOTIVES. 


127 


SPARKS  FROM  TEST  No.   14. — Continued. 

160 


Actual  size  and  number  of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance 
of  1 60  feet  from  the  centre  of  the 
track. 


Actual  size  and  number  of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance 
of  200  feet  from  the  centre  of  the 
track. 


Actual  size  and  number  of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance 
of  250  feet  from  the  centre  of  the 
track. 


14 


Actual    size    and   number   of 
sparks  falling  within  an  area  of 
484  square  inches,  at  a  distance    .. 
°f  35°  feet  from  the  centre  of  the 
track. 


200 


250 


350 


128  LOCOMOTIVE  SPARKS. 

32.  A  Summarized  Statement  of  Results  of  experiments 
to  determine  the  spread  of  sparks  along  the  right-of-way  is  as 
follows : 

1.  The  greatest  number  of  sparks  fell  at  from   35  to   150 
feet  from  the  centre  of  the  track.    It  may  therefore  be  assumed, 
from  the  data  at  hand,  that  the  possibility  of  fire  is  greatest 
within  these  limits. 

2.  With  a  few  exceptions,  the  pans  nearest  the  track,  i.e., 
from  15  to  20  feet,  caught  but  few  sparks.      Local  conditions, 
due  to  air-currents  about  the  train,  may  in  part  be  responsible 
for  this. 

3.  No  scorching  of  the  cotton  in  the  pans  was  in  any  case 
observed.      This  may  be  accounted  for  by  the  fact  that  during 
the  time  the  tests  were  run  (in  April  and   May)  the  tempera- 
tures were  comparatively  low.     Some  of  the  larger  sparks  were 
quite  warm,  however,  when  picked  up  immediately  after  falling. 

4.  Beyond  125  feet  from  the  centre  of  the  track  the  sparks 
were   of  such   character   as  to  preclude  any  possibility  of  fire 
from  them. 

5.  In   March,  preceding  the  tests,  when   a   light   crust   of 
snow  covered  the  ground,  it  was  possible  to  trace  evidence  of 
dust  from  passing  locomotives  at  a  distance  of  800  feet  from 
the  track.      The  wind  velocity  was  high — about  20  miles  an 
hour.      Nothing  in  this  observation  should  be  interpreted  as  in 
conflict  with  the  statement  of  the  preceding  paragraph. 


CHAPTER    VII. 

THEORETICAL    CONSIDERATIONS     AFFECTING    THE 
SPREAD    OF   SPARKS   BY   MOVING   LOCOMOTIVES. 

33.  THE   results   of  actual   observations  upon  the  size   of 
sparks,  and  the  extent  of  area  over  which  they  are  distributed 
by  moving  locomotives,  have  been  presented  in  the  preceding" 
chapter.      It  is  the  purpose   of  the  present  chapter  to  discuss 
the  various  forces  affecting  the  spread  of  sparks  and  to  show 
their  relation  one  to  another,  so  that  if  certain   conditions  are 
assumed  to  prevail,  the  resulting  effect  can  be  predicted. 

34.  Preliminary  Conceptions. — All  change  of  motion  is 
the  result  of  force.      If  a  body  freed  from  the  influence  of  all 
forces  save  that  of  gravity  be  thrown  vertically  upward,  the 
action  of  gravity  will  cause  it  to  return  by  the  same  path   as 
that  by  which  it  rose  until  it  rests  upon  the   same  spot  from 
whence  it  started.      Or,  if  a  body  in  the  air  is  freed  from  the 
influence  of  all  forces  excepting  that  of  the  wind,  it  will  move 
with  the  wind  in  the  direction  in  which  the  wind  is  moving  and 
at  the   same    velocity    as  the    wind.       The  effect    of   several 
forces  acting  at  the  same  time  upon  a  given  body  was  origi- 
nally   stated  by    Newton    as  follows:     -"When    any    number 
of  forces   act  simultaneously  upon   a  body,  then   whether  the 
body  be   originally  at  rest  or  in   motion,  each  force  produces 
exactly  the  same  effect  in  magnitude  and  direction  as  if  acting 
alone."      This  principle  is  often  called  the  Law  of  Independ- 
ence of  Motion.     By  this  law  it  will  be  seen  that  if  a  body,  as, 

129 


13°  LOCOMOTIVE  SPARKS. 

for  example,  a  spark,  be  projected  upwards  in  the  presence  of 
a  strong  wind,  it  will  move  upward  in  response  to  the  initial 
impulse  to  a  certain  height  and  will  then  descend.  This 
upward  and  downward  movement  will  extend  over  the  same 
vertical  distances,  and  will  take  the  same  time  as  would  be  the 
case  if  the  wind  were  not  blowing.  On  the  other  hand,  a 
spark  thus  projected  will  respond  to  the  influence  of  the  wind 
throughout  the  time  it  remains  in  the  air  to  the  same  extent 
that  it  would  if  the  force  of  gravitation  were  not  in  action. 
Being,  therefore,  under  the  influence  of  gravity,  which  tends 
to  retard  or  to  produce  motion  in  vertical  lines,  and  under  the 
influence  of  the  wind,  which  tends  to  produce  motion  in  hori- 
zontal lines,  the  actual  path  followed  will  be  a  curve. 

35.  The  Path  and  Horizontal  Displacement  of  a  Body 
Assumed  to  be  in  Air  at  a  given  Distance  from  the  Ground 
and  Free  to  Move  Both  in  Response  to  Gravity  and  to  the 
Influence  of  Wind  Acting  in  a  Horizontal  Direction.— If, 
now,  we  assume  a  body,  as  A,  Fig.  60,  held  in  the  air  at  a 
given  distance  from  the  ground  and  subject  to  the  action  of 
gravity  and  to  the  influence  of  wind,  it  will,  when  released, 
move  in  obedience  to  both  of  these  forces;  it  will  fall  through 
the  height  //  to  the  ground,  and  in  the  time  occupied  in  falling 
the  wind  will  have  caused  it  to  move  horizontally  through  the 
distance  d,  the  path  followed  by  the  body  being  described  by 
the  curve  AB.  From  this  general  statement  it  is  possible  to 
express  mathematically  the  relation  between  the  height  of  the 
fall  h  and  the  horizontal  displacement  d,  which  is 


/aX 

-  V  ? ' 


in  which  d  is  the  horizontal  distance  traversed  in  feet;  z/f  the 
velocity  of  wind  in   feet  per  second;  //,  the  height  through 


SPREAD    OF  SPARKS   BY   MO  YIN  G    LOCOMOTIVES. 


which  the  body  is  allowed  to  fall  in  response  to  gravity;  and 
j  the  acceleration  due  to  gravity,  or  32.2.*     By  use  of  this 


FIG.  60. 


*  The  full  demonstration  is  as  follows  : 

Let  v  =  velocity  of  wind  in  feet  per  second; 

h  =  iiitial  height  in  feet  which  a  freely  falling  body  may  be  above 

the  ground; 
d  =  horizontal    distance    in    feet    through    which    the  body   would 

move  in  falling  to  the  ground; 
/  =  time  of  descent  in  seconds; 

g  =  acceleration  due  to  gravity  (=  32.2  feet  per  second). 
If  the  effect  of  the  wind  velocity  alone  is  considered,  then 

d  =  vt, (i) 

whence 

t  =  * (2) 

V 

If   the    effect   of  the  acceleration  of   gravity  alone   is  considered,  then, 
from  the  law  of  falling  bodies, 

h  =  &/*,    ...........     (3) 

whence 


t  —  if  — 


(4) 


But  when  the  forces  act  simultaneously,  the  time  /,  required  to  fall  the 
distance  h,  is  the  same  as  the  time  required  to  travel  the  distance  d.      Ex- 


132 


LOCOMOTIVE  SPARKS. 


formula  the  values  for  d  shown  by  Table  IX  have  been 
obtained.  The  table  shows  how  far  it  is  possible  for  a  particle 
to  be  borne  by  the  wind  starting  from  points  at  various  dis- 
tances from  the  ground  and  influenced  by  wind  of  different 
velocities. 

TABLE  IX. 

SHOWING  THE  HORIZONTAL  DISPLACEMENT  OF  A  BODY 
UNDER  THE  INFLUENCE  OF  WIND  OF  DIFFERENT  VE- 
LOCITIES, WHILE  FALLING  FROM  DIFFERENT  HEIGHTS. 


Velocity  of 
Wind. 

Initial  Height  in  Feet  from  which  the  Body  is  Assumed  to  Start. 

Feet 

Miles 

per 

Second. 

Hour. 

15 

20 

25 

30 

40 

50 

75 

100 

2.Q3 

2 

2.8 

3-3 

3-6 

4.0 

4.6 

5-2 

6-3 

7.3 

7-34 

5 

7-o 

8.1 

9-i 

10.  0 

ii.  5 

13-0 

15-8 

18.3 

11.74 

8 

ii.  3 

13-0 

14-5 

16.0 

18.4 

20.8 

25-3 

29.2 

17.60 

12 

16.9 

19-5 

21.8 

23-9 

27.6 

31-2 

38.0 

43-8 

23-47 

16 

22.5 

26.0 

29.1 

3i-9 

36.8 

41.5 

50.5 

58.4 

29-34 

20 

28.2 

32.6 

36.4 

39-9 

46.1 

51.9 

63-3 

73-o 

44.01 

30 

42.2 

48.8 

54-6 

59-8 

69.1 

77.9 

94-9 

109.6 

58.68 

40 

56-3 

65.1 

72.7 

79-8 

92.1 

103.8 

126.6 

146.1 

73-35 

50 

70.4 

81.4 

90.9 

99-7 

II5-I 

129.8 

158.2 

182.6 

88.02 

60 

84-5 

97-7 

109.1 

II9-7 

138.2 

155.8 

189.9 

219.1 

For  example,  when  the  initial  height  //  of  the  body  above  the 
ground  is  20  feet  and  the  wind  velocity  is  12  miles  per  hour, 
the  horizontal  distance  d  is  19.5  feet.  Again,  when  the 
initial  height  is  50  feet  and  the  wind  velocity  is  40  miles  per 
hour,  the  distance  is  103.8  feet.  It  is  to  be  noted  that  the 


pressing  this  fact  mathematically  by  equating  the   right-hand  .members  of 
(2)  and  (4),  we  get 


'  =  4/2- 

v  g 


whence 


d  = 


(5) 


(6) 


SPREAD   OF  SPARKS  BY  MO V 'ING   LOCOMOTIVES. 


133 


equation  and  the  table  derived  by  its  use,  presuppose  that  the 
body  in  question  is  free  from  the  action  of  all  forces  except  that 
of  gravity  and  that  of  the  horizontal  movement  of  the  wind. 
Under  this  assumption  the  values  given  are  absolute.  As  a 
matter  of  fact,  a  body  in  falling  in  air  is  retarded  somewhat  by 
the  resistance  of  the  atmosphere,  and  would  therefore  be  a 
trifle  longer  in  its  descent  than  is  allowed  by  the  formula,  with 
the  result  that  the  horizontal  distance  would  also  be  greater. 
In  another  paragraph  an  attempt  will  be  made  to  correct  for 
this  influence.  For  the  present  the'  results  as  given  should  be 
accepted  as  defining  the  physical  relationship  applicable  to  a 
freely  falling  body. 


FIG.  61. 

35.  The  Path  and  Horizontal  Displacement  of  a  Body 
Projected  Vertically  Upward  when  Free  to  Respond  to  the 
Influence  of  Gravity  and  of  Wind  Acting  Horizontally. — 

Fig.  6 1  is  a  graphical  representation  of  the  path  followed  by  a 
freely  falling  body  which  when  starting  from  a  definite  point, 
as  A ,  is  projected  vertically  upward  while  subject  to  the  action 


134  LOCOMOTIVE  SPARKS. 

of  the  wind  under  the  influence  of  which  it  is  assumed  to  move 
horizontally.  The  arrow  g  shows  the  direction  of  the  force  of 
gravity.  The  arrow  v  shows  the  direction  of  the  constant 
wind  velocity.  The  curved  line  A  BCD  shows  the  path  which 
the  body  will  follow  in  its  journey  to  the  ground.  The  maxi- 
mum height,  7/2 ,  is  not  reached  until  some  distance,  !l ,  from  the 
initial  position.  From  this  point  the  body  gradually  falls  to 
the  ground  through  a  horizontal  distance  /2.  The  total  hori- 
zontal distance*  traversed  by  the  body  is  expressed  by 


d  —  i1 

g 

Table  X  gives  values  for  d  as  obtained  from  formula  (b) 
by  the    substitution   of  successive  values  of  //.,  and   7'.      The 

*  Let  v\  =  velocity  of  wind  in  feet  per  second; 

hi  =  initial  height  in  feet  of  body  above  ground; 

h?,  =  maximum  height  in  feet  of  body  above  ground; 

g   =  acceleration  of  gravity  (=  32.2  feet  per  second); 

d   =  horizontal  distance  in  feet    through   which  the  body  would 

move  in  falling  to  the  ground. 

The  path  of  the  body  is  divided  into  two  parts:  that  from  A  to  B,  and 
that  from  B  to  D. 

The    horizontal    distance    traversed    in    passing    from    A    to    B   is    ex- 
pressed by 


The  horizontal  distance  traversed  in  passing   from  B  to  D  is  expressed 
by 


......     ....     (2) 

But  the  total  horizontal  distance  is  /,  +  /a  =  d.     Therefore 


,          i«    i        A9          ,  f  . 

d  =  v      ----  \-  v      -  --  .......    (3) 

o 


or 


SPREAD  OF  SPARKS  BY  MOVING   LOCOMOTIVES. 


initial  height  //x  is  taken  at  15  feet.*  For  example,  when  the 
maximum  height  to  which  the  body  rises  is  20  feet  and  the 
wind  velocity  is  12  miles  per  hour,  the  horizontal  distance  d 
through  which  the  body  will  travel  in  falling  to  the  ground  is 
found  to  be  29.4  feet.  If  the  maximum  height  be  increased 
to  50  feet  and  the  wind  velocity  to  40  miles  per  hour,  the 
horizontal  distance  d  is  found  to  be  191 .4  ;  if  the  wind  velocity 
be  60  miles,  the  displacement  becomes  247.8  feet. 

TABLE  X. 

SHOWING  THE  HORIZONTAL  DISPLACEMENT  OF  A  BODY 
PROJECTED  VERTICALLY  UPWARD  FROM  AN  INITIAL 
HEIGHT  OF  FIFTEEN  FEET  AND  FREE  TO  MOVE  BOTH 
IN  RESPONSE  TO  GRAVITY  AND  TO  THE  INFLUENCE  OF 
WIND  ACTING  IN  A  HORIZONTAL  DIRECTION. 


Velocity  of 
Wind. 

Maximum  Height  in  Feet  to  which  Body  is  Projected. 

Feet 

Miles 

per 

per 

15 

20 

25 

3° 

4o 

50 

75 

TOO 

Second. 

Hour. 

2-93 

2 

2-8 

4.9 

5-9 

6.8 

8-3 

9.6 

12.0 

I4.I 

7-34 

5 

7.0 

12.2 

14.8 

17.0 

20.7 

23-9 

30.0 

35-2 

11.74 

8 

"•3 

19.6 

23-7 

27-3 

33-o 

38.3 

48.0 

56.2 

17.60 

12 

16.9 

29.4 

35-6 

40.9 

49.6 

57-4 

71-9 

84-4 

23-47 

16 

22-5 

39-2 

47-5 

54-6 

66.1 

76.5 

95-i 

112.5 

29-34 

20 

28.2 

50.0 

59-4 

68.2 

82.6 

95-7 

119.9 

140.6 

44.01 

30 

42.2 

73-5 

89.1 

102.3 

123.9 

143-5 

179.9 

210.9 

58.68 

40 

56.3 

98.0 

118.7 

136.4 

165.2 

I9I-3 

239-8 

281.2 

73-35 

50 

70.4 

122.5 

148.4 

170.5 

206.5 

239.1 

299.8 

351-5 

88.02 

60 

84-5 

147.0 

178.1 

204.6 

247.8 

286.9 

359-7 

421.9 

While  the  results  given  in  Tables  IX  and  X  are  not  with- 
out value  as  a  basis  from  which  to  predict  the  probable  flight 
of  sparks,  it  should  be  remembered  that  the  body  in  the  pre- 
ceding illustrations  is  assumed  to  fall  freely,  as  in  a  vacuum, 
and  when  liberated  to  at  once  partake  of  the  velocity  of  the 

*  An   initial   height  of  15   feet  represents  approximately   the  distance 
of  the  top  of  a  locomotive-stack  above  the  ground. 


I36  LOCOMOTIVE  SPARKS. 

wind.  We  are  now  to  consider  what  are  the  modifications  in 
the  assumptions  and  results  which  will  follow  the  substitution 
of  a  spark  for  a  freely  falling  body. 

37.  The  Horizontal  Displacement  of  Sparks  which  are 
Assumed  to  be  in  Air  Free  to  Respond  to  the  Action  of 
Gravity  and  to  the  Influence  of  Wind  Acting  Horizontally. 
— The  theoretical  considerations  of  the  preceding  paragraphs 
relative  to  the  action  of  any  freely  falling  body  is  applicable  to 
a  spark  after  leaving  the  stack  of  a  locomotive.  The  values 
given  in  Tables  IX  and  X  do  not,  however,  accurately  repre- 
sent the  horizontal  distances  which  a  spark  may  be  assumed 
to  travel  after  leaving  the  stack,  owing  to  the  fact  that  these 
values  were  computed  by  using  32.2  as  the  acceleration  due 
to  gravity.  This  value  represents  the  velocity  of  a  body 
starting  from  rest  and  falling  in  vacuum  for  one  second.  A 
spark  is  a  comparatively  light  body,  and  the  resistance  of  the 
atmosphere  impedes  its  movements;  hence,  after  its  emission 
from  a  locomotive  stack,  it  will  remain  in  the  air  for  a  longer 
time  than  a  heavier  or  more  dense  body.  In  other  words, 
the  apparent  value  of  the  acceleration  of  gravity  for  a  spark  is 
less  than  32.2  feet  per  second.  Before  tables  can  be  con- 
structed, similar  in  form  to  those  representing  the  movement  of 
a  freely  falling  body  (Tables  IX  and  X),  it  is  first  necessary 
to  determine  the  acceleration  for  a  falling  spark  in  air.  Such  a 
determination  has  been  made  experimentally.  To  serve  in  this 
research,  special  apparatus  was  designed,  the  essential  details 
of  which  are  shown  in  Fig.  62.  It  consists  of  three  vertical 
rods,  the  two  outer  ones  being  placed  before  a  graduated  scale 
showing  feet  and  inches.  Upon  each  of  these  two  outer  rods 
slides  a  horizontal  arm,  at  the  outer  end  of  which  is  fastened 
a  cylindrical  tube,  open  at  both  ends.  Two  movable  hori- 
zontal arms  extend  from  the  central  rod.  At  the  extremities 


SPREAD   OF  SPARKS  BY  MOVING   LOCOMOTIVES. 


137 


FIG.  62. 


I38  LOCOMOTIVE  SPARKS. 

of  each  of  these  arms  is  fastened  a  flat  piece  of  metal  for 
covering  the  bottom  of  the  tubes.  In  conducting  the  experi- 
ments the  tube  A,  Fig.  62,  was  first  placed  at  some  predeter 
mined  height  7il  ,  and  the  movable  bottom  C  adjusted  to  the 
lower  end  of  the  tube.  The  tube  B  was  then  placed  at  some 
height  less  than  //x,  and  its  bottom  piece  likewise  adjusted.  In 
the  upper  tube,  A,  was  next  placed  a  small  lead  bullet.  In  the 
lower  tube,  B,  was  placed  a  spark  taken  from  the  front-end  of  a 
locomotive.  A  quick  rotation  of  the  central  rod  served  to 
withdraw  the  bottoms  from  both  tubes  simultaneously  and  to 
allow  their  contents,  in  one  case  a  bullet,  and  in  the  other  case 
a  spark  or  cinder,  to  fall  to  the  floor.  By  repeated  trials  the 
tube  B  was  finally  placed  at  a  height  such  that  the  spark  and 
bullet  both  reached  the  floor  at  the  same  instant.  By  noting 
the  heights  /^  and  /i.2  from  which  the  two  bodies  dropped, 
respectively,  and  from  a  knowledge  of  the  acceleration  01 
gravity  for  the  bullet  (assumed  to  be  32.2),  the  acceleration  for 
the  falling  spark  was  determined.* 

*  Let  //i  =  height  in  feet  of  bullet  above  the  floor; 
Ji-i  —  height  in  feet  of  spark  above  the  floor; 
/     =  time  in  seconds  of  descent  for  spark  and  bullet; 
g    =  32-2; 
a    =  acceleration  for  spark. 

Then,  from  the  law  of  falling  bodies: 
For  the  bullet 

/Si  =  \&*  ...........     (i) 

whence 


For  the  spark 

**  =  i«'2>     .  .  .........     (3) 

whence 


But  the  time  of  descent,  /*,  is  the  same  for  the  bullet  as  for  the  spark. 


SPREAD   OF  SPARKS  BY  MOVING   LOCOMOTIVES.  139 

A  long  series  of  experiments  was  thus  conducted,  and  from 
the  results  obtained  the  average  value  of  the  acceleration  for  a 
falling  spark  was  found  to  be  22.72.  The  sparks  experimented 
with  were  both  cold  and  incandescent,  but  differences  due  to 
changes  in  the  temperature  of  the  spark  were  too  small  to  be 
detected. 

Tables  XI  and  XII  have  been  computed  under  conditions 
identical  with  Tables  IX  and  X,  respectively,  except  that  the 
value  of  a  (22.72)  was  used  instead  of  g  (32.2).  It  is  to  be 
noted  that  the  values  of  d  given  in  Tables  XI  and  XII  are 
uniformly  greater  than  those  given  in  Tables  IX  and  X, 
respectively,  a  fact  entirely  consistent  with  the  conditions 
imposed. 

38.  The  Effect  of  the  Direction  of  the  Wind  on  the  Dis- 
tance from  the  Track  to  which  Sparks  may  be  Carried. — It 
is  obvious  that  a  spark  projected  from  a  moving  locomotive 
will,  other  things  being  equal,  travel  a  maximum  distance  from 
the  track  when  the  direction  of  the  wind  is  at  right  angles  to 
the  direction  of  the  track.  The  values  given  in  the  preceding 
tables  may  be  taken  to  represent  maximum  distances  from  the 
track  at  which  sparks  \vill  alight  when  the  direction  of  the  wind 
is  at  right  angles  to  the  track.  For  all  other  directions  of 
wind  relative  to  track,  the  distances  from  the  track  at  which 
sparks  will  find  lodgment  will  be  less  than  those  given  in  the 
tables.  The  diagram  Fig.  63  will  serve  to  make  these  state- 
Expressing  this  mathematically  by  equating  the  right-hand  members  of  (2) 
and  (4), 

2/5,         2//2 

—  ::_-..  ........      (5) 

Therefore 

•     • (6) 


140 


LOCOMOTIVE  SPARKS. 

TABLE  XL 


SHOWING  THE  HORIZONTAL  DISPLACEMENT  OF  A  SPARK 
UNDER  THE  INFLUENCE  OF  WIND  OF  DIFFERENT  VE- 
LOCITIES, WHILE  FALLING  FROM  DIFFERENT  HEIGHTS. 


Velocity  of 

Wind. 

Feet 

Miles 

per 
Second. 

Hour. 

15 

20 

2-93 

2 

3-3 

3-8 

7-34 

5 

8.2 

9-5 

11.74 

8 

i3-i 

15-2 

17.60 

12 

19.7 

22.7 

23-47 

16 

26.2 

30.3 

29-34 

20 

32.8 

37-9 

44-01 

30 

49-2 

56.8 

58.68 

40 

65.6 

75-8 

73-35 

50 

81.9 

94-7 

88.02 

60 

98.3 

II3-7 

Initial  Height  of  Spark  in  Feet. 


25 

3° 

40 

50 

75 

roo 

4.2 

4.6 

5-4 

6.0 

7-4 

8-5 

10.6 

ii.  6 

13-4 

15-  1 

18.4 

21.3 

16.9 

18.6 

21.4 

24.2 

29.5 

34-o 

25-4 

27-9 

32.2 

36.3 

44-2 

5i.o 

33-9 

37-1 

42.9 

48-3 

58.9 

68.0 

42-3 

46.4 

53-6 

60.4 

73-7 

85.0 

63-5 

69.6 

80.4 

90.6 

110.5 

127-5 

84.7 

92.9 

107.2 

120.9 

147.4 

170.0 

105.8 

116.1 

134.0 

151-1 

184.2 

212.5 

127.7 

139-3 

160.8 

181.3 

221  .O 

255-0 

TABLE  XII. 

SHOWING  THE  HORIZONTAL  DISPLACEMENT  OF  A  SPARK 
PROJECTED  VERTICALLY  UPWARD  FROM  AN  INITIAL 
HEIGHT  OF  FIFTEEN  FEET  AND  FREE  TO  MOVE  BOTH 
IN  RESPONSE  TO  GRAVITY  AND  TO  THE  INFLUENCE  OF 
WIND  ACTING  IN  A  HORIZONTAL  DIRECTION. 


Velocity  of 
Wind. 


Maximum  Height  in  Feet  to  which  the  Spark  is  Projected. 


Feet 

Miles 

per 

per 

15 

20 

25 

30 

40 

50 

75 

IOO 

Second. 

Hour. 

2.93 

2 

3-3 

5-7 

6.9 

7-8 

9.6 

II.  I 

13.9 

16.4 

7.34 

5 

8.2 

14-3 

17.3 

19.8 

24.0 

27.8 

34-9 

40.9 

11-74 

8 

13-1 

22.8 

27.6 

31-8 

38.5 

44-5 

55-8 

65.5 

17.60 

12 

19.7 

34-2 

41.5 

47.6 

57-7 

66.8 

83-7 

98.2 

23-47 

16 

26.2 

45-6 

55-3 

63-5 

76.9 

89.1 

in.  7 

130.9 

29.34 

20 

32.8 

57-0 

69.1 

79-4 

96.1 

in.  3 

139.6 

163.7 

44.01 

30 

49.2 

85-5 

103-7 

119.2 

144.2 

167.0 

209.4 

245.5 

58.68 

40 

65.5 

114.0 

138.2 

158-8 

192.3 

222.7 

279.1 

327.4 

73-35 

50 

81.9 

142.5 

172.8 

198.5 

240.4 

278.3 

348.9 

409.2 

88.02 

60 

98.3 

171.1 

207.3 

238.1 

288.4 

334-0 

418.7 

491.0 

SPREAD   OF  SPARKS  BY  MOVING  LOCOMOTIVES.  141 

ments  clear.  Table  XIII  gives  multipliers  by  the  use  of 
which  the  values  in  Tables  IX  to  XII,  inclusive,  can  be  made 
to  show  the  distance  from  the  centre  of  the  track  at  which  a 
spark  will  alight  under  the  influence  of  winds  which  blow  at 
various  angles  with  the  direction  of  the  train's  motion.* 

TABLE   XIII. 


Angle  £,   Fig.  63,  which   Direction   of   Wind 
makes  with  Direction  of  the  Train's  Motion. 

Multipliers  to  be  Used. 

30 

•  500 

45 

.707 

60 

.866 

For  example,  from  Table  XI  it  will  be  found  that  when  the 
initial  height  is  20  feet  and  the  wind  velocity  is  1 2  miles  per 
hour,  the  maximum  distance  traversed  by  the  spark  will  be 
22.7  feet.  This  distance  assumes  the  wind  to  blow  at  right 
angles  with  the  track.  If  the  wind  is  assumed  to  blow  at  an 
angle  of  45°  with  the  track,  this  value  of  d  would  become 
.707  X  22.734  =  16.0.  In  a  similar  manner  corrections  may 
be  applied  to  all  the  tables. 

39.  Effect  of  Train's  Motion  on  the  Distance  from  the 
Centre  of  the  Track  at  which  Sparks  Find  Lodgment.  - 
The  train's  motion  does  not  affect  the  maximum  distance  from 
the  centre  of  the  track  at  which  the  spark  will  alight  except 
in  so  far  as  incidental  air-currents  may  have  their  influence. 
The  present  purpose  deals  with  the  well-known  physical  con- 
ditions only.  The  ejected  spark  has  the  same  forward  motion 

*  The  distance  AB(¥\g.  63)  traversed  by  the  spark  is  the  same  whatever 
may  be  the  direction  of  the  wind.  The  distance  CB  varies  with  the  angle 
(p>,  or 

CB  =  (AB)  sin  0 (i) 


142 


LOCOMOTIVE  SPARKS. 


CO/ 


f 


SPREAD  OF  SPARKS  BY  MOVING  LOCOMOTIVES.          143 


144  LOCOMOTIVE  SPARKS. 

at  the  time  it  is  sent  forth  from  the  stack  as  the  locomotive 
itself,  and  it  retains  something  of  this  motion  until  the  initial 
energy  is  entirely  absorbed  by  frictional  contact  with  the 
atmosphere.  That  such  motion  does  not  affect  the  distance 
from  the  centre  of  the  track  traversed  by  the  spark  will  appear 
from  Fig.  64,  which  shows  that  if  the  locomotive  were  at  rest, 
with  the  wind  blowing  across  the  track,  the  spark  leaving  A 
would  follow  the  path  d  and  land  at  a  point  B.  If  the  loco- 
motive were  in  motion,  the  spark  starting  from  A  would  follow 
a  curved  path,  landing  at  C.  The  distance  CB  depends  upon 
the  velocity  of  the  train,  but  in  either  case  the  distances  AB 
and  DC  depend  upon  the  velocity  of  the  wind  and  are  equal. 


CHAPTER   VIII. 
CHANCES   OF   FIRE   FROM   SPARKS. 

40.  A  Review  of  Certain  Facts  already  Presented. — In 

the  preceding  chapters  there  has  been  disclosed  much  that  is 
important  concerning  the  chances  of  fire  from  locomotive 
sparks.  In  a  review  of  this  matter  it  is  well,  first  of  all,  to 
note  that  the  production  of  sparks  constitutes  one  of  the  neces- 
sary manifestations  attending  the  action  of  a  modern  locomo- 
tive. It  is  not  possible  under  any  circumstances  to  entirely 
suppress  them.  Other  things  remaining  the  same,  the  amount 
of  solid  matter  thrown  from  the  stack  increases  when  the 
intensity  of  the  draft-action  is  increased,  so  that  when  the  loco- 
motive is  worked  to  high  power  more  sparks  are  thrown  than 
when  the  power  developed  is  low.  Their  volume  varies,  also, 
with  the  character  of  fuel ;  for  example,  anthracite  coal  gives 
off  but  few  sparks,  and  these  are  composed  chiefly  of  ash, 
while  the  light  and  friable  lignite  coals,  such  as  must  be  used 
on  many  Western  roads,  are  prolific  spark-producers. 

The  composition  of  sparks  varies  from  that  of  ash  such  as 
results  from  the  complete  combustion  of  fuel  to  that  of  fuel  but 
slightly  charred.  Ash-sparks  are  incapable  of  carrying  fire, 
but  sparks  composed  of  partially  burned  fuel  may  appear  as 
small  coals  of  coke  which  glow  in  the  dark,  or  as  incandescent 
or  even  as  flaming  particles.  It  is  noteworthy  that  incan- 
descent or  flaming  sparks  constitute  but  a  small  proportion  of 
all  the  solid  matter  ejected.  It  appears,  also,  that  those 

145 


146  LOCOMOTIVE  SPARKS. 

particles  which  are  composed  of  combustible  material  and 
which  are,  therefore,  capable  of  carrying  fire  are,  except  in 
rare  instances,  deprived  of  fire  by  violent  contact  with  the 
mechanism  of  the  front-end  against  which  they  are  driven,  and 
by  gathering  moisture  from  the  stream  of  exhaust-steam  which 
serves  to  send  them  out  into  the  atmosphere.  In  the  vernac- 
ular of  the  road,  they  are  ' '  killed. ' ' 

The  size  of  sparks,  as  estimated  from  appearances  about 
the  stack,  is  often  deceptive.  Incandescent  particles  emitted, 
especially  at  night,  appear  large,  when  in  reality  they  are  very 
small.  An  investigation  of  the  front-end  mechanism,  through 
which  all  sparks  must  pass  before  they  can  reach  the  outer  air, 
will  generally  show  that  it  is  impossible  for  sparks  larger  than 
a  half-kernel  of  corn  to  be  emitted.  An  examination  of  sparks 
which  perchance  collect  in  quiet  corners  about  railroad  stations 
will  supply  added  evidence  tending  to  confirm  this  statement; 
the  largest  spark  that  can  be  found  generally  being  much 
smaller  than  a  half-kernel  of  corn. 

The  fact  has  been  mentioned  that  but  few  of  all  the  sparks 
delivered  carry  fire,  and  many  of  these  are  doubtless  small  in 
size.  The  experiments  in  gathering  sparks  from  passing  loco- 
motives, the  results  of  which  are  recorded  in  a  preceding 
chapter,  failed  to  disclose  a  single  instance  in  which  a  falling 
spark  sufficed  to  scorch  common,  unbleached  cotton  muslin 
which  was  laid  in  the  bottom  of  the  collecting-pans  to  receive 
them.  These  observations  were  made  in  the  months  of  April 
and  May.  It  is  the  testimony  of  many  experienced  railway 
men  that  atmospheric  conditions  have  much  to  do  with  the 
fire-carrying  properties  of  sparks;  that  in  winter,  when  the  air 
and  all  combustible  material  upon  which  sparks  may  fall  are 
cold,  fires  from  sparks  never  occur;  that  it  is  only  in  midsum- 
mer, when  the  temperature  of  the  atmosphere  is  high,  and 


CHANCES  OF  FIRE  FROM  SPARKS.  147 

when  long-continued  dry  weather  has  prepared  the  grass  of 
the  roadside  for  a  fire,  and  a  hot  sun  has  warmed  it  to  a  high 
temperature,  that  fires  from  sparks  are,  under  normal  condi- 
tions, possible.  So  small  is  the  heat-carrying  power  of  a  spark 
from  a  locomotive  in  good  order  that  it  may  be  doubted  whether 
such  a  spark  was  ever  the  means  of  communicating  fire  to  the 
roof  of  a  building,  even  when  under  the  influence  of  a  summer 
sun  the  roof  had  become  well  dried  and  highly  heated,  except 
in  cases  where  it  may  have  fallen  on  materials  more  finely 
divided  than  shingles. 

The  distance  traversed  by  sparks,  as  shown  by  observa- 
tions along  the  track,  establishes  the  danger-line  very  close  to 
the  track.  Both  a  large  percentage  of  all  sparks  thrown  out 
and  the  largest  individual  specimens  were  found,  in  the  experi- 
ments herein  recorded,  within  a  distance  of  100  feet  from  the 
centre  of  the  track.  This  distance  fixes  the  danger-line.  As 
tending  to  further  confirm  this  statement,  the  testimony  of 
those  who  have  had  occasion  to  observe  the  progress  of  fires 
originating  from  locomotives  is  to  the  effect  that  while  objects 
located  at  considerable  distances  from  the  track  sometimes 
burn,  the  firing  of  such  objects  is  not  the  immediate  result  of  a 
spark  from  a  locomotive;  that  the  initial  fire  from  the  locomotive 
spark  is  invariably  started  upon  the  right-of-way  inside  of  the 
fence;  that  this  initial  fire,  which  is  invariably  in  the  grass,  is 
communicated  to  a  pile  of  ties  or  of  refuse  materials  or  to  the 
right-of-way  fence,  the  burning  embers  of  which  are  wind- 
borne  to  more  distant  objects.  The  fact,  therefore,  that  a 
building  60  or  So  yards  from  the  track  may  burn  should  not 
be  accepted  as  evidence  that  sparks  from  a  locomotive  will 
carry  fire  to  such  distances,  though  a  spark  may  have  been  an 
indirect  cause  of  the  fire.  In  all  such  cases,  however,  there 
will  be  evidence  of  the  initial  fire. 


148  LOCOMOTIVE  SPARKS. 

Against  the  statements  of  the  preceding  paragraphs  may 
be  urged  the  fact  that  persons  standing  at  considerable  dis- 
tances from  the  track  sometimes  feel  upon  their  face  and  hands 
the  impact  of  particles  discharged  from  a  passing  locomotive, 
the  experience  indicating  that  such  particles  do  travel  consider- 
able distances.  A  close  inspection  of  the  particles  which  thus 
impress  themselves  will,  however,  show  them  to  be  very 
minute,  so  small  in  fact  as  to  be  hardly  more  than  finely 
divided  dust,  wholly  incapable  of  carrying  fire.  The  hands 
and  face  are  so  very  sensitive  that  the  impress  of  such  material 
gives  one  the  impression  of  being  bombarded  by  fragments  of 
considerable  size,  but  the  slightest  examination  will  suffice  to 
convince  him  of  his  mistake.  Obviously,  the  present  dis- 
cussion is  not  concerned  with  the  distribution  of  these  dust- 
like  sparks. 

Finally,  as  tending  to  still  further  confirm  the  conclusions 
already  stated,  it  appears  that  if,  in  his  efforts  to  make  sparks 
travel  long  distances  from  the  track,  one  abandons  all  con- 
sideration of  local  conditions,  and  bases  an  estimate  on  the 
physical  laws  governing  the  movement  of  all  bodies  in  air,  he 
will  be  obliged  to  assume  that  sparks  rise  to  a  very  great 
height,  or  that  they  are  influenced  by  a  very  strong  wind, 
before  his  results  will  carry  the  sparks  very  far  afield.  In 
other  words,  it  may  be  readily  shown  by  the  application  of 
well-known  laws  applying  to  falling  bodies  that  sparks  suffi- 
ciently large  to  carry  fire  must,  under  ordinary  conditions  of 
discharge  and  of  wind  velocity,  strike  the  ground  within  com- 
paratively short  distances  from  the  track.  A  concise  statement 
of  the  facts  in  this  case  is  presented  elsewhere. 

41.  The  Influence  of  Air-currents  about  a  Moving  Train. 
—A  moving  train  is  surrounded  by  a  zone  of  air  which  par- 
takes more  or  less  completely  of  the  motion  of  the  train  itself, 


CHANCES   OF  FIRE  FROM  SPARKS.  149 

depending  upon  the  thickness  of  the  enveloping  film  which  one 
chooses  to  consider,  and  upon  the  part  of  the  train  to  which  it 
is  assumed  to  apply.  The  head  of  the  moving  train  entering 
undisturbed  air  creates  strong  lines  of  pressure  which  wrap 
themselves  in  wave-like  form  about  its  initial  end  and  are 
carried  along  by  it.  At  the  rear  of  the  moving  train  the 
atmospheric  pressure  is  less  than  normal,  and  the  air  rushes  in 
from  all  sides  in  strong  currents  to  fill  the  space  left  by  the 
receding  train.  The  effect  of  eddies  thus  formed  upon  the 
course  of  sparks  discharged  by  the  locomotive  at  the  head  of 
the  train  is  a  subject  which  probably  has  not  been  carefully 
studied.  There  is,  however,  much  to  sustain  the  theory  that 
such  sparks  do  not  escape  the  influence  of  the  eddies,  that 
they  are  caught  up  by  them,  held  within  their  influence,  and 
finally  drawn  into  the  zone  of  low  pressure  at  the  rear  of  the 
train.  In  so  far  as  this  argument  applies  it  serves  to  show 
that  sparks  which  would  otherwise  be  carried  by  the  wind  at 
right  angles  to  the  track  are  in  reality  carried  along  with  the 
strong  currents  of  air  which  move  with  the  train  until  they 
settle  upon  the  track  at  its  rear. 

An  observer  at  the  rear  of  a  rapidly  moving  train  cannot 
"but  be  impressed  by  the  vigor  of  the  air-currents  which  are 
drawn  in  upon  the  track  in  its  rear,  reaching  out  to  and  influ- 
encing the  motion  of  objects  far  distant  from  the  track  itself. 
The  smoke  from  a  locomotive  at  the  head  of  a  rapidly  moving 
train  trails  close  on  the  top  of  the  train  and  drops  as  it  passes 
over  the  last  car,  regardless  of  the  direction  or  velocity  of  the 
wind. 

Professor  Francis  E.  Nipher,  who  has  conducted  elaborate 
experiments  in  determining  the  velocity  of  air-currents  imme- 
diately about  a  moving  train,  argues  that  the  effect  of  a  moving 
train  upon  the  atmosphere  is  such  as  to  draw  objects  in  its 


150  LOCOMOTIVE  SPARKS. 

vicinity  to  itself.  Hats  which  are  blown  from  the  heads  of 
persons  standing  on  a  station  platform  are  drawn  under  the 
train.  Bed-mattresses  rolled  into  bundles  and  piled  upon  the 
platform  of  a  freight  station  have  been  observed  to  topple  over 
under  the  influence  of  the  wind  from  a  passing  train,  and  to 
be  drawn  under  the  wheels.*  These  considerations  imply  that 
sparks  are  not  always  free  to  respond  to  the  influences  of  the 
wind,  but  that  they  are  constrained  in  their  motion,  and  that 
the  effect  of  the  resistance  is  to  hold  them  to  the  course  of  the 
train. 

42.  Sparks  from  a  Locomotive  and  Sparks  from  a  Fixed 
Fire  are  not  Subjected  to  the  Same  Influences. — It  is  a  matter 
of  common  knowledge  that  sparks  and  sometimes  brands 
arising  from  a  fixed  fire  are  carried  by  the  wind  over  long  dis- 
tances. Fragments  arising  from  a  burning  building,  for 
example,  are  not  infrequently  carried  a  half  mile  or  more. 
The  question  at  once  suggests  itself  as  to  why  it  is  that  brands 
from  a  burning  building  will  travel  such  distances,  while  sparks 
from  a  locomotive  are  borne  but  a  few  feet.  The  answer  is 
to  be  found  in  the  different  conditions  which  prevail  in  the  two 
cases.  Thus  the  shape  of  many  of  the  fragments  arising  from 
a  burning  building  well  fits  them  for  sailing  in  the  air.  When 
such  a  fragment,  as,  for  example,  a  shingle,  is  blazing,  it 
carries  with  it  its  own  sustaining  power.  The  heat  from  the 
flame  stimulates  ascending  currents  of  air  which,  acting  upon 
the  broad  surface  of  the  fragment,  tend  to  keep  it  in  air  while 
the  wind  bears  it  away.  Again,  a  fixed  fire  serves  to  establish 
strong  and  far-reaching  air-currents.  If  the  wind  is  light,  the 


*  Professor  Nipher's  discussion  and  mathematical  deductions  concern- 
ing "  The  Frictional  Effect  of  Railway  Trains  upon  the  Air  "  will  be  found 
in  the  Transactions  of  the  Academy  of  Science  of  St.  Louis,  vol.  x,  No.  10, 
issued  Nov.  12,  1900. 


CHANCES   OF  FIRE  FROM  SPARKS.  151 

column  of  heated  air  rises  as  the  fire  proceeds  to  greater  and 
greater  heights,  the  activity  of  the  upward  current  becomes 
intensely  strong,  and  particles  which  are  caught  within  its 
influence  are  borne  to  very  great  heights.  When  these  are  of 
the  sort  which  have  been  described,  they  settle  very  slowly 
after  being  released  from  the  influence  of  the  upward  current, 
and  drift  away  with  the  wind.  If  a  large  fixed  fire  occurs  in 
the  presence  of  a  strong  wind,  the  heated  current  constitutes  a 
vast  lane  moving  obliquely  upward,  reaching  out  over  territory 
miles  distant  from  the  source  of  heat,  bearing  fragments  and 
burning  brands.  In  either  case  the  power  of  the  fixed  fire  in 
spreading  sparks  and  brands  lies  in  the  fact  that  the  heat 
developed  in  any  one  moment  is  supplemented  by  that  which 
is  developed  the  next  moment.  The  currents  of  air  which  are 
set  in  motion  by  the  heat  developed  during  any  one  period 
are  accelerated  by  the  heat  of  a  later  period.  The  whole 
process  is  cumulative,  and,  other  things  being  the  same,  the 
larger  the  fire  the  more  rapid  the  currents  become  and  the 
farther  they  extend  their  influence. 

In  striking  contrast  with  all  this  are  the  conditions  which 
surround  the  discharge  from  the  stack  of  a  locomotive.  The 
sparks  delivered  are  comparatively  heavy  in  proportion  to  the 
extent  of  their  exposed  surface,  and  are  thus  not  easily  borne 
by  ascending  air-currents.  They  are  so  small  that,  while  they 
give  up  the  heat  they  carry  very  rapidly,  the  amount  liberated 
is  insufficient  to  stimulate  to  any  marked  degree  upward  cur- 
rents of  air  about  them.  Again,  the  total  amount  of  heat 
liberated  from  a  locomotive  is  small  compared  with  that 
generated  by  a  burning  building  and,  hence,  all  effects  are  less 
pronounced.  As  sparks  go  out  of  the  locomotive  stack,  they 
find  no  far-reaching  current  to  carry  them  on,  for  each  exhaust 
from  the  stack  is  into  undisturbed  air.  There  is  absolutely  no 


152  LOCOMOTIVE  SPARKS. 

cumulative  effect.  The  heat-energy  delivered  is  dissipated  in 
the  atmosphere  which  canopies  the  whole  length  of  track,  the 
discharge  of  a  single  minute  being  perhaps  distributed  over  a 
mile  of  territory.  There  is,  therefore,  nothing  to  buoy  up 
the  locomotive  spark  but  the  initial  velocity  with  which  it  is 
projected.  From  these  considerations  it  should  be  evident 
that  conclusions  based  on  observations  in  connection  with 
fixed  fires  are  not  applicable  to  the  conditions  affecting  sparks 
in  locomotive  service. 


APPENDIX. 


THE    PURDUE    UNIVERSITY    LOCOMOTIVE 
TESTING-PLANT. 

43.  Development  of  the  Plant. — The  discussions  of  the 
preceding  chapters  so  frequently  refer  to  results  which  have 
been  obtained  in  connection  with  the  experimental  locomotive 
of  Purdue  University  that  it  appears  desirable  that  there  be 
added  some  description  of  this  locomotive  and  of  the  mechan- 
ism upon  which  it  runs. 

The  purpose  of  the  experimental  testing-plant  is  to  permit 
the  action  of  a  locomotive  to  be  studied  with  the  same  ease 
and  degree  of  accuracy  as  attends  the  study  of  a  stationary 
engine.  This  is  accomplished  by  converting,  in  effect,  the 
locomotive  into  a  stationary  engine,  but  by  doing  this  in  such  a 
manner  that  the  locomotive  remains  free  to  exercise  all  its 
usual  functions.  The  experimental  locomotive  is  a  machine 
which  in  size  and  in  the  completeness  of  its  appointments  is 
capable  of  doing  immediate  service  on  the  road  at  the  head  of 
a  train. 

The  plan  of  mounting  a  locomotive  for  experimental  pur- 
poses as  developed  at  Purdue  involves  (i)  supporting  wheels 
carried  by  shafts  running  in  fixed  bearings,  to  receive  the  loco- 
motive drivers  and  to  turn  with  them;  (2)  brakes  mounted  on 

153 


154  APPENDIX. 

the  shafts  of  the  supporting  wheels,  which  should  have  suffi- 
cient capacity  to  absorb  continuously  the  maximum  power  of 
the  locomotive;  (3)  a  traction  dynamometer  to  measure  the 
horizontal  moving  force  of  the  engine  on  the  supporting 
wheels. 

Assume  an  engine,  thus  mounted,  to  be  running  in  forward 
motion,  the  supporting  wheels,  the  faces  of  which  constitute 
the  track,  revolving  freely  in  rolling  contact  with  the  drivers. 
The  locomotive  as  a  whole  being  at  rest,  the  track  under  it 
(the  tops  of  the  supporting  wheels)  is  forced  to  move  back- 
ward. If  now  the  supporting  wheels  be  retarded  in  their 
motion,  as,  for  example,  by  the  action  of  friction-brakes,  the 
engine  must,  as  a  result,  tend  to  move  off  them.  If  they  be 
stopped,  the  drivers  must  stop  or  slip.  Whether  the  resistance 
be  great  or  small,  the  force  which  is  transmitted  from  the 
driver  to  the  supporting  wheel  to  overcome  the  resistance  will, 
reappear  as  a  stress  in  the  draw-bar,  which  alone  holds  the 
locomotive  to  its  place  upon  the  supporting  wheels.  The 
dynamometer  constitutes  the  fixed  point  with  which  the  draw- 
bar connects  and  serves  to  measure  stresses  transmitted. 

It  is  evident  from  these  considerations  that  the  tractive 
power  of  such  a  locomotive  may  be  increased  or  diminished  by 
simply  varying  the  resistance  against  which  the  supporting 
wheels  turn,  and  that  the  readings  of  the  traction  dynamom- 
eter will  always  serve  as  a  basis  for  calculating  work  done  at 
the  draw-bar.  A  locomotive  thus  mounted  can  be  run  either 
ahead  or  aback  under  any  desired  load  and  at  any  speed ;  and, 
while  thus  run,  its  performance  can  be  determined  with  a 
degree  of  accuracy  and  completeness  far  excelling  that  which 
it  is  possible  to  secure  under  ordinary  conditions  on  the  road. 

The  matter  of  having  a  locomotive  mounted  upon  the  plan 
described  was  discussed  at  Purdue  early  in  the  year  1890,  and 


APPENDIX.  155 

it  was  so  well  received  that  in  May,  1891,  an  order  was  given 
the  Schenectady  Locomotive  Works  for  a  17"  X  24"  eight- 
wheeled  engine.  The  details  of  the  mounting  were  worked 
out  during  the  two  months  following.  In  September  the  loco- 
motive had  been  delivered,  and  it  was  in  operation  before  the 
close  of  the  year. 

This  plant,  the  first  of  its  kind,  is  described  in  detail  in  a 
paper  entitled  "  An  Experimental  Locomotive,"  which  was 
read  before  the  American  Society  of  Mechanical  Engineers  at 
the  San  Francisco  meeting  in  May,  1892. 

On  the  23d  of  January,  1894,  the  plant  was  destroyed  by 
fire.  Plans  for  reconstruction  were  at  once  entered  upon  and 
vigorously  pushed.  The  damaged  engine  was  extricated  from 
the  ruins  of  the  building  and  repaired.  The  mounting  ma- 
chinery was  redesigned,  improved  in  details,  and  a  separate 
building  was  built  for  its  accommodation.  It  is  this  recon- 
structed plant  (Figs.  65  to  69)  which  has  served  in  all  work 
the  results  of  which  are  referred  to  in  preceding  chapters. 
Recently  the  original  locomotive,  now  known  as  Schenectady 
No.  I,  has  given  way  to  one  of  heavier  and  more  modern 
design,  but  the  later  machine  (Schenectady  No.  2)  is  not  asso- 
ciated with  any  of  the  results  which  are  herein  described. 

A  detailed  description  of  the  present  plant  is  next  pre- 
sented : 

44.  The  Wheel-foundation. — By  reference  to  Figs.  65  and 
66  it  will  be  seen  that  there  is  provided  a  wheel-foundation,  A, 
of  nearly  25  feet  in  length.  This  is  more  than  sufficient  to 
include  the  driving-wheel  base  of  any  standard  eight-,  ten-,  or 
twelve-wheeled  engine.  For  engines  having  six  wheels 
coupled,  a  third  supporting  axle  will  be  added  to  those  shown, 
and  for  engines  having  eight  wheels  coupled  four  new  axles, 
having  wheels  of  smaller  diameter  than  those  shown,  will  be 
used. 


156 


APPENDIX. 


APPENDIX. 


'57 


COAL  SUPPLr 


I58  APPENDIX. 

The  wheel-foundation  carries  cast-iron  bed-plates,  to  which 
are  secured  pedestals  for  the  support  of  the  axle-boxes.  The 
lower  flanges  of  the  pedestals  are  slotted  and  the  bed-plates 
have  threaded  holes  spaced  along  their  length.  By  these 
means  the  pedestals  may  be  adjusted  to  any  position  along  the 
length  of  the  foundation. 

The  boxes  in  use  at  present  are  plain  babbitted  shaft-bear- 
ings, and  between  each  bearing  and  its  pedestal  a  wooden 
cushion  is  inserted.  A  bearing  has  been  designed  for  use  in 
some  special  experiments  which  provides  for  the  suspension  of 
the  axle  from  springs,  but  this  bearing  has  not  yet  been  used. 

The  outer  edges  of  the  wheel-foundation  are  topped  by 
timbers  to  which  the  brake-cases  are  anchored.  The  brakes 
which  absorb  the  power  of  the  engine  are  the  ones  which  were 
used  in  the  original  plant.  They  are  constructed  upon  a  prin- 
ciple developed  by  Professor  Geo.  I.  Alden,  and  their  capacity 
and  wearing  qualities  are  beyond  question.  The  load  upon 
them  is  controlled  by  varying  the  pressure  of  water  which 
circulates  through  them  and  carries  away  the  heat.  The  water- 
pressure  acts  upon  stationary  copper  plates  which  are  forced 
against  a  moving  cast-iron  disc,  thereby  producing  friction. 
No  provision  is  made  for  determining  the  load  upon  each 
brake,  but  the  loads  may  be  equalized  by  equalizing  the  flow 
and  pressure  of  the  cooling  water.  The  sum  of  these  loads 
plus  the  friction  of  the  axles  in  their  boxes  makes  up  the  sum- 
total  of  work  to  be  done ;  this  work  must  be  given  out  from 
the  locomotive  drivers.  It  all  reappears  in  the  form  of  draw- 
bar stress,  and  its  value  is  shown  by  the  traction  dynamometer. 
An  elaborate  system  of  piping  (not  shown  in  figures)  provides 
for  the  circulation  of  the  cooling  water  for  the  brakes  at  what- 
ever point  along  the  length  of  the  foundation  they  may  be 
located. 


APPENDIX.  159 

45.  The  Traction  Dynamometer. — The  vibrating  character 
of  the  stresses  to  be  measured  makes  the  design  of  the  traction 
dynamometer  a  matter  of  some  difficulty.  The  dynamometer 
of  the  original  plant  consisted  of  an  inexpensive  system  of 
levers  attached  to  a  heavy  framework  of  wood,  the  vibrations 
being  controlled  by  dashpots.  In  the  present  construction 
wood  as  a  support  is  entirely  abandoned  and  a  massive  brick 
pier,  well  stayed  with  iron  rods,  has  been  substituted.  The 
dynamometer  itself  (B,  Figs.  65  and  66)  consists  of  the 
weighing-head  of  an  Emery  testing-machine,  the  hydraulic 
support  of  which  is  capable  not  only  of  transmitting  the  stress 
it  receives,  but  also  of  withstanding  the  rapid  vibrations  which 
the  draw-bar  transmits  to  it.  The  apparatus  is  of  30,000 
pounds  capacity. 

In  view  of  the  enormous  force  which  a  locomotive  is 
capable  of  exerting  it  would  appear,  at  first  sight,  that  an  error 
of  50  or  even  100  pounds  in  the  determination  of  draw-bar 
stresses  would  be  of  slight  consequence,  and  that  great  accu- 
racy in  this  matter  is  not  required.  Under  some  conditions 
this  conclusion  is  correct,  but  under  others  it  is  far  from  true. 
The  work  done  at  the  draw-bar  is  the  product  of  the  force 
exerted  multiplied  by  the  space  passed  over;  if  the  force  ex- 
erted be  great  and  the  speed  low,  a  small  error  in  the  draw- 
bar stress  is  not  a  matter  of  great  importance ;  but  if  the  reverse 
conditions  exist — if  the  speed  be  high  and  the  draw-bar  stress 
low — then  it  is  absolutely  necessary  that  the  draw-bar  stress 
be  determined  with  great  accuracy.  Moreover,  high  speeds 
necessarily  involve  low  draw-bar  stresses.  A  locomotive 
which  at  10  miles  an  hour  may  pull  12,000  pounds  will  have 
difficulty,  when  running  60  miles  per  hour,  in  maintaining  a 
pull  of  2500  pounds.  These  conditions  have  prompted  the 
Purdue  authorities  to  make  extraordinary  efforts  to  secure 


160  APPENDIX. 

accurate  measurements  at  the  draw-bar,  and .  they  serve  as  a 
sufficient  justification  of  the  heavy  expenditure  involved  in  the 
purchase  of  the  Emery  machine. 

As  is  well  known,  the  arrangement  of  the  hydraulic  support 
of  the  Emery  testing-machine  permits  the  weighing-scale  to 
be  at  any  convenient  distance  from  the  point  where  the  stresses 
are  received.  Figs.  65  and  66  show  only  the  receiving  end 
of  the  apparatus.  The  draw-bar  connects  with  this  apparatus 
by  a  ball-joint,  which  leaves  its  outer  end  free  to  respond  to 
the  movement  of  the  locomotive  on  its  springs.  A  threaded 
sleeve  allows  the  draw-bar  to  be  lengthened  or  shortened  for 
a  final  adjustment  of  the  locomotive  to  its  position  upon  the 
supporting  wheels;  and  finally,  to  meet  the  proportions  of 
different  locomotives,  provision  is  made  for  a  vertical  adjust- 
ment of  the  entire  head  of  the  machine  upon  its  frame. 

46.  The  Superstructure. — Figs.  67  and  68  show  the  ar- 
rangement of  floors.  The  "  visitors'  floor  "  (Fig.  68)  and  the 
fixed  floors  adjoining  are  at  the  level  of  the  rail.  The  open  space 
over  the  wheel-foundation  is  of  such  dimensions  as  will  easily 
accommodate  an  engine  having  a  long  driving-wheel  base, 
movable  or  temporary  floors  being  used  to  fill  in  about  each 
different  engine,  as  may  be  found  convenient.  The  temporary 
flooring  shown  is  that  employed  for  the  locomotive  Schenec- 
tady  No.  I. 

The  level  of  the  * '  tender-floor  "is  at  a  sufficient  height 
above  the  rail  to  serve  as  a  platform  from  which  to  fire.  At 
the  rear  is  a  runway  leading  to  the  coal-room,  the  floor  of 
which  is  somewhat  lower  than  the  tender  floor.  A  platform 
scale  is  set  flush  with  the  floor  at  the  head  of  the  runway. 
During  tests  the  scale  is  used  for  weighing  the  coal  which  is 
delivered  to  the  fireman. 

The  feed-water  tank,  from  which  the  injectors  draw  their 


APPENDIX. 


161 


i62 


APPENDIX. 


APPENDIX.  163 

supply,  is  shown  in  the  lower  right-hand  corner  of  Fig.  68. 
Above  this  supply-tank  are  two  small  calibrated  tanks  so 
arranged  that  one  may  be  filled  while  the  other  is  discharging. 

The  steam-pump  shown  on  the  visitors'  floor  is  for  the 
purpose  of  supplying  water  under  pressure  to  the  friction-brakes 
which  load  the  engine. 

The  conditions  under  which  the  engine  is  operated  are  at 
all  times  within  the  control  of  a  single  person,  whose  place  is 
just  at  the  right  of  the  steps  leading  to  the  tender-floor.  From 
this  position  he  can  see  the  throttle  and  reverse-lever  and 
observe  all  that  goes  on  in  the  cab.  At  his  right  is  the 
dynamometer  scale-case,  wherein  is  shown  the  load  at  the 
draw-bar;  in  front  are  the  gages  giving  the  water-pressure 
on  the  brakes ;  and  under  his  hand  are  the  valves  controlling 
the  circulation  of  water  through  the  brakes. 

No  attempt  has  been  made  in  these  drawings  to  show  small 
accessory  apparatus,  neither  does  it  seem  necessary  to  give  an 
•enumeration  of  such  details. 

47.  The  Building. — Fig.  69  presents  several  views  of  the 
locomotive  building.  The  entrance-door,  which  opens  upon 
the  visitors'  floor,  is  shown  in  the  south  elevation.  It  is 
approached  from  the  general  laboratory,  45  feet  away. 

The  north  and  west  elevations  show  the  roof-construction, 
whereby  the  upper  end  of  the  locomotive  stack  is  made  to 
stand  outside  of  the  building.  The  roof-sections  shown  may 
be  entirely  removed  and  a  door  in  the  cross-wall,  which 
extends  between  the  removable  roof  and  the  main  roof,  pro- 
vides ample  height  for  the  admission  of  the  locomotive  to  the 
building.  A  window  in  this  door  (Fig.  68)  serves  .to  give  the 
fireman  a  clear  view  of  the  top  of  the  locomotive  stack  from 
his  place  in  the  cab,  a  condition  which  is  essential  to  good 
work  in  firing.  Above  the  stack  is  a  pipe  to  convey  the  smoke 


i64 


APPENDIX. 


APPENDIX.  165 

clear  of  the  building.  To  meet  a  change  in  the  location  of  the 
stack  this  pipe  may  be  moved  to  any  position  along  the  length 
of  the  removable  roof. 

The  plan  of  the  building  (Fig.  69)  shows  the  arrangement 
of  tracks  for  the  locomotive  and  of  those  used  for  supplying 
coal. 


INDEX. 


PAGR 

Acceleration  of  sparks,  experiments  to  determine 136-138 

Air-currents  about  a  train 148-150 

Alden  friction-brake 158 

Analysis  of  sparks,  chemical , . . , 33 

Anthracite  coal  for  locomotives 12,  13 

Arch,  function  of  brick 38 

Area  of  grate,  limitations  upon 11-14 

Ash  sparks   145 

Atlantic  type  of  locomotives 12 

Authorities  on  the  front-end 72~73 

Baffle-plate:  see  Diaphragm. 

Baltimore  and  Ohio  R.  R.,  front-end  used  on 69 

Basket-netting , 45 

Bell,  J.  Snowden,  front-end  arrangements  by 52-72 

Bell  front-end 69-72 

Blast-pipe:  see  Exhaust-pipe. 

Boiler,  Wootten 12,  13 

Bonnet 50 

Borries,  Herr  von,  experiments  on  exhaust-jet  by 72 

Brakes,  Alden  fricti;>n 158 

Brick  arch 38 

Camden  &  Atlantic  R.  R.,  front-end  used  on 69 

Chances  of  fire  from  sparks 145-152 

Chemical  analysis  of  sparks 33 

Chicago,  Burlington  and  Quincy  R.  R.,  front-end  used  on 61 

Cinder-pot 40,  53, 

Cinder-pocket:  see  Cinder -pot. 

167 


1 68  INDEX. 

PAGB 

Cinders  and  sparks,  definition  of 17-18 

"         "         "       production  of 18 

"          "          «'       experiments  to  determine  extent  of  loss  by 27-32 

"         "         "       size  of 21-25 

'•          "         "       conclusions  on 35~3° 

(See  also  Sparks.) 

Coal  equivalent  of  sparks 32~35 

Coal  tests  of  locomotives 31 

Coburn  front-end 69 

Combustion,  rates  of 9-10 

' '  conditions  governing  rates  of 10-14 

' '  effect  of  draft  upon 14 

' '  experiments  on  rates  of. ... 14 

Comparison  of  locomotive  and  stationary  plants 6 

Cone  :   see  Diamond-stack. 

Deflector-plate  :  see  Diaphragm. 

Diamond-stack 50 

Diaphragm,  function  of 41 

' '  arrangements  of 41-43 

Dill.  Mr.  J.  B.,  experiments  by 89 

Direction  of  wind,  effect  upon  spread  of  sparks  of 139-141 

Distances  traversed  by  sparks 95-143 

Distribution  of  sparks  along  right-of-way 95-128 

"     within  stack 85-88 

Door,  fire      7 

Draft,  definition  of 14 

1 '      factors  producing 14 

"      effect  of 14-15 

"       measurement  of H-I5 

' '       comparison  of 15 

"      appliances 37~73 

"      pipes  :  see  Petticoat-pipes. 

Ducas,  Mr.  Chas.,  experiments  by 89 

Dynamometer,  traction 159 

Exhaust-jet,  experiments  with 74-^5 

"  "  appearance  of -  .  84 

"  "  character  of 79-^5 

"  ' '  velocity  of 78,  82,  85 

Exhaust-nozzle  :  see  Exhaust-pipe. 

Exhaust-pipe,  function  of 47 

4 '  "  forms  of 46-48 

Exhaust-tip,  function  of 49 

"  "  forms  of 49-50 


INDEX.  169 

PAGE 

Experiments  on  rates  of  combustion 7rr:T4~ 

"  ' '  draft  and  combustion 15 

"  to  determine  spark-  and  cinder-losses 27~32 

"  "         "          spread  of  sparks 85-128 

11  "         "          fuel- value  of  sparks 33 

"  "         "          acceleration  of  falling  sparks 136-138 

Extended  front-end  :  see  Front-end. 

Falling  bodies,  action  of 129-144 

Fire-box  :  see  Furnace. 

Fire-door  :  definition  of J 

Fire-grate,  definition  of ^ 

"        "      size  of 12 

Fire  from  sparks,  chances  of 145-152 

Fixed-fire,  sparks  from  a 150-152 

Front-end,  a  typical 38-41 

"          arrangements S3~72 

"          recommended  by  Master  Mechanics'  Association 53,  58,  61,  65 

"          used  on  the  C.,  B.  &  Q.  R.  R 61 

"  "     "     "   C.  I.  &  L.  R.  R.:  see  Coburn  Front-end. 

"  "     "     "  Camden  and  Atlantic  R.  R 69 

"  '«     ««     "   Mexican  Central  R.  R 53-65 

<'  «     "     4<   Norfolk  and  Western  R.  R 58 

»  <l     "     <;   Pennsylvania  R.  R 65 

«  "     "     "   Pittsburgh,  Bessemer  and  Lake  Erie  R.  R 69-72 

"  tt     it     it   Union  Pacific  R.  R 53 

"         the  Bell 69-72 

u          the  Coburn 69 

< '          authorities  on 72~73 

Front-ends,  kinds  of 5°-52 

Front-sheet:  see  Tube-sheet. 

Fuel-loss  by  cinders  and  sparks 27-32 

Fuel-value  of  sparks 32-35 

Furnace,  locomotive 7 

Furnace-action  in  locomotive 7 

Garstang,  Mr.  Wm.,  tests  by 31 

Grate,  fire 7 

Grate-area,  limitations  upon  size  of. 11-14 

Heating  value  of  sparks 32-35 

Herr,  Mr.  Edwin  M.,  experiments  by 72 

Independence  of  motion,  law  of. 129 


1 7°  INDEX. 

PAGB 

Jet,  exhaust 74-85 

"   appearance  of. < 84 

"   character  of 79-85 

"   velocity  of 78,  82,  85 

Limitations  affecting  design  of  stationary  power-plants 1-3 

"  "  ii      tt  moving  power-plants 2,  3,  4 

Locomotive  testing  plant 153-165 

Loss  of  fuel  by  cinders  and  sparks 27~32 

Master  Mechanics'  Association,  front-end  recommended  by 53,  58,  61,  65 

"  "  "  experiments  upon  exhaust-jet  by 79-85 

Mexican  Central  R.  R.,  front-end  used  on 53,  61,  65 

Motion,  law  of  independence  of 129 

Motion  of  train,  effect  upon  spread  of  sparks  of 141-144 

Moving  power-plants,  limitations  affecting  design  of 2,  3,  4 

"  "  comparison  of  stationary  plants  with. . » 6 

Mug,  Mr.  George  F.,  experiments  by 89 

Netting,  function  of 43 

"        arrangements  of 43~45 

"        basket 45 

Newton's  law  of  motion 129 

Nipher,  Prof.  Francis  E.,  experiments  by 149-150 

Norfolk  and  Western  R.  R.,  front-end  used  on 58 

Nozzle,  exhaust:  see  Exhaust-pipe. 

Open  stack 50 

Pennsylvania  R.  R. ,  front-end  used  on. 65 

Petticoat-pipe 45 

Pipe,  exhaust 46-48 

Pittsburgh,  Bessemer  and  Lake  Erie  R.  R.,  front-end  used  on 69,  72 

Plate,  deflector:  see  Diaphragm. 
Pocket,  cinder:  see  Cinder-pot. 

Pot,  cinder 40,  53 

Prevention  of  sparks,  difficulties  besetting 37,  38 

"  "        "       devices  employed  for  the 38-45 

Quereau,  Mr.  C.  H. ,  report  by 42-43 

Quayle,  Mr.  Robert,  experiments  by 72 

Rates  of  combustion 9-10 

Rates  of  combustion,  conditions  governing 10-14 

"      "  "  experiments  on 14 

Right-of-way,  distribution  of  sparks  along 95-128 


INDEX.  I71 

PAGE 

Sauvage  Mr.  E. ,  report  by 50 

Sheet,  front:  see  Tube- sheet. 

Sheet,  tube 7 

Short  front-end:   see  Front-end. 

Size  of  cinders  and  sparks 21,  25,  111-128 

Smoke-box:  see  Front-end. 

Smoke-stack,  functions  of 50 

"  kinds  of 53~7-2 

Spark-prevention,  difficulties  besetting 37~3^ 

1 '  devices  employed  for 38-45 

Sparks,  definition  of 18 

11  production  of 16,  18 

"  ash 145 

"  heating  value  of 32~35 

"  chemical  analysis  of 33 

Spark-losses,  methods  of  determining 19-21 

' '  experiments  to  determine 27~32 

Spark-  and  cinder-losses,  conclusions  concerning 3 5-36 

Sparks,  distribution  within  stack  of 85-88 

"  method  of  determining  spread  of 90-92 

"  spread  of 89-128 

"  summary  of  tests  to  determine  spread  of 97-9$ 

< '  at  various  distances  from  track 1 1 1-128 

"  theory  of  spread  of. 129-144 

"  acceleration  of  gravity  for  falling 136-139 

tl  effect  of  direction  of  wind  upon  distribution  of 139-141 

"  "  "  motion  of  train  upon  distribution  of 141-144 

"  chances  of  fire  from 145-152 

"  from  fixed  fire 150-152 

Stack:  see  Smoke-stack. 

Stack,  diamond 50 

' '  open 50 

Standard  front-end 53,  58,  61,  65 

Stationary  power-plants,  limitations  affecting  design  of 1-3 

"  "  comparison  of  moving  power-plants  with 6 

"  "  rates  of  combustion  employed  in 9 

"  "  draft  in 15 

Test,  Chas.  D. ,  chemical  analyses  by 33 

Tests  of  coal 31 

Testing  plant,  locomotive 153-165 

Theory  of  spread  of  sparks 129-144 

Tip,  exhaust 49,  50 

Train,  air-currents  about 148-150 


172  INDEX. 

PAtiE 

Traction  dynamometer *59.  l6° 

Trajectories  of  falling  bodies •   I3I~I33 

Troske.  Inspector,  experiments  by 72 

Tubes  7 

Tube-sheet 7 

Union  Pacific  R.  R.,  front-end  used  on 53 

Velocity  of  exhaust-jet • 78>  82>  85 

Wheel  foundation  of  testing-plant ISS^S8 

Wootten  boiler I2>  X3 


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